Search results for: fabric mechanical properties

Authors: Danielle C. B. Honorato, Rafael H. Carvalho, Adriana L. Soares, Ana Paula F. R. L. Bracarense, Paulo D. Guarnieri, Massami Shimokomaki, Elza I. Ida

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Over the past decade, the Brazilian production of turkey meat increased by more than 50%, indicating that the turkey meat is considered a great potential for the Brazilian economy contributing to the growth of agribusiness at the marketing international scenario. However, significant color changes may occur during its processing leading to the pale, soft and exudative (PSE) appearance on the surface of breast meat due to the low water holding capacity (WHC). Changes in PSE meat functional properties occur due to the myofibrils proteins denaturation caused by a rapid postmortem glycolysis resulting in a rapid pH decline while the carcass temperature is still warm. The aim of this study was to analyze the physical, chemical and histological characteristics of PSE turkey meat obtained from a Brazilian commercial processing plant. The turkey breasts samples were collected (n=64) at the processing line and classified as PSE at L* ≥ 53 value. The pH was also analyzed after L* measurement. In sequence, PSE meat samples were evaluated for WHC, cooking loss (CL), shear force (SF), myofibril fragmentation index (MFI), protein denaturation (PD) and histological evaluation. The abnormal color samples presented lower pH values, 16% lower fiber diameter, 11% lower SF and 2% lower WHC than those classified as normal. The CL, PD and MFI were, respectively, 9%, 18% and 4% higher in PSE samples. The Pearson correlation between the L* values and CL, PD and MFI was positive, while that SF and pH values presented negative correlation. Under light microscopy, a shrinking of PSE muscle cell diameter was approximately 16% shorter in relation to normal samples and an extracellular enlargement of endomysium and perimysium sheaths as the consequence of higher water contents lost as observed previously by lower WHC values. Thus, the results showed that PSE turkey breast meat presented significant changes in their physical, chemical and histological characteristics that may impair its functional properties.

Keywords: functional properties, histological evaluation, meat quality, PSE

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Authors: Zaida Perez-Bassart, Berta Polanco-Estibalez, Maria Jose Fabra, Amparo Lopez-Rubio, Antonio Martinez-Abad

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Mushroom production has enormously increased in recent years, not only as food products but also for applications in pharmaceuticals, nutraceuticals, and cosmetics. Consequently, interest in its chemical composition, nutritional value, and therapeutic properties has also increased. Fungi are rich in bioactive compounds such as polysaccharides, polyphenols, glycopeptides, and ergosterol, of great medicinal value, but within polysaccharides, β-glucans are the most prominent molecules. They are formed by D-glucose monomers, linked by β-glucosidic bonds β-(1,3) with side chains linked by β-(1,6) bonds. The number and position of the β-(1,6) branches strongly influence the arrangement of the tertiary structure, which, together with the molecular weight, determine the different attributed bioactivities (immunostimulating, anticancer, antimicrobial, prebiotic, etc.) and physico-chemical properties (solubility, bioaccessibility, viscosity or emulsifying). On the other hand, there is a growing interest in the study of fungi as an alternative source of chitin obtained from the by-products of the fungal industry. In this work, a cascade extraction process using aqueous neutral and alkaline treatments was carried out for Grifola frondosa and Lentinula edodes, and the compositional analysis and functional properties of each fraction were characterized. Interestingly, the first fraction obtained by using aqueous treatment at room temperature was the richest in polysaccharides, proteins, and polyphenols, thus obtaining a greater antioxidant capacity than in the other fractions. In contrast, the fractions obtained by alkaline treatments showed a higher degree of β-glucans purification compared to aqueous extractions but a lower extraction yield. Results revealed the different structural recalcitrance of β-glucans, preferentially linked to proteins or chitin depending on the fungus type, which had a direct impact on the functionalities and bioactivities of each fraction.

Keywords: fungi, mushroom, β-glucans, chitin

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Authors: Acacia A. Salomão, Willian L. Gomes da Silva, Gustavo G. Shimamoto, Matthieu Tubino

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Biodiesel physical and chemical properties depend on the raw material composition used in its synthesis. Saturated fatty acid esters confer high oxidative stability, while unsaturated fatty acid esters improve the cold flow properties. In this study, an alternative vegetal source - the macauba kernel oil - was used in the biodiesel synthesis instead of conventional sources. Macauba can be collected from native palm trees and is found in several regions in Brazil. Its oil is a promising source when compared to several other oils commonly obtained from food products, such as soybean, corn or canola oil, due to its specific characteristics. However, the usage of biodiesel made from macauba oil alone is not recommended due to the difficulty of producing macauba in large quantities. For this reason, this project proposes the usage of blends of the macauba oil with conventional oils. These blends were prepared by mixing the macauba biodiesel with biodiesels obtained from soybean, corn, and from residual frying oil, in the following proportions: 20:80, 50:50 e 80:20 (w/w). Three parameters were evaluated, using the standard methods, in order to check the quality of the produced biofuel and its blends: oxidative stability, cold filter plugging point (CFPP), and iodine value. The induction period (IP) expresses the oxidative stability of the biodiesel, the CFPP expresses the lowest temperature in which the biodiesel flows through a filter without plugging the system and the iodine value is a measure of the number of double bonds in a sample. The biodiesels obtained from soybean, residual frying oil and corn presented iodine values higher than 110 g/100 g, low oxidative stability and low CFPP. The IP values obtained from these biodiesels were lower than 8 h, which is below the recommended standard value. On the other hand, the CFPP value was found within the allowed limit (5 ºC is the maximum). Regarding the macauba biodiesel, a low iodine value was observed (31.6 g/100 g), which indicates the presence of high content of saturated fatty acid esters. The presence of saturated fatty acid esters should imply in a high oxidative stability (which was found accordingly, with IP = 64 h), and high CFPP, but curiously the latter was not observed (-3 ºC). This behavior can be explained by looking at the size of the carbon chains, as 65% of this biodiesel is composed by short chain saturated fatty acid esters (less than 14 carbons). The high oxidative stability and the low CFPP of macauba biodiesel are what make this biofuel a promising source. The soybean, corn and residual frying oil biodiesels also have low CFPP, but low oxidative stability. Therefore the blends proposed in this work, if compared to the common biodiesels, maintain the flow properties but present enhanced oxidative stability.

Keywords: biodiesel, blends, macauba kernel oil, stability oxidative

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Authors: Laima Silina, Ilze Gramatina, Liga Skudra, Tatjana Rakcejeva

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The aim of the current research was to determine quality parameters changes of dried venison during storage. Protein, fat and moisture content dynamics as well microbiological quality was analyzed. For the experiments the meat (0.02×4.00×7.00 cm) pieces were marinated in “teriyaki sauce” marinade (composition: teriyaki sauce, sweet and sour sauce, taco sauce, soy sauce, American BBQ sauce hickory, sesame oil, garlic, garlic salt, tabasco red pepper sauce) at 4±2°C temperature for 48±1h. Sodium monophosphate (E339) was also added in part of marinade to improve the meat textural properties. After marinating, meat samples were dried in microwave-vacuum drier MUSSON–1, packaged in vacuum pouches made from polymer film (PA/PE) with barrier properties and storage for 4 months at 18±1°C temperature in dark place. Dried venison samples were analyzed after 0, 35, 91 and 112 days of storage. During the storage total plate counts of dried venison samples significantly (p<0.05) increased. No significant differences in the content of protein, fat and moisture were detected when analyzing dried meat samples during storage and comparing them with the chemical parameters of just dried meat.

Keywords: drying, microwave-vacuum drier, quality, venison

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Authors: Anant Pandey, Kanika Sharma, Vibha Chopra, Shaila Bahl, Pratik Kumar, S. P. Lochab, Birendra Singh

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This paper reports the thermoluminescence (TL) properties of nanocrystalline CaSO₄ activated by Ce, Sm, and Dy. TL properties are investigated by chiefly changing the dopant element and also by varying the concentration of the dopant elements (from 0.05 mol % to 0.5 mol %) so as to establish the optimized dopant concentration for each of the activators. The method of salt preparation used is the typical chemical co-precipitation method and the technique used for characterization of the prepared samples is the X-Ray Diffraction (XRD) technique. Further, the phosphors are irradiated with gamma radiation from Co-60 (1.25 MeV) source (dose range- 30 Gy to 500 Gy). The optimized concentration (vis-a-vis TL peak intensity) of activator for CaSO₄:Ce is found to be 0.2 mol %, for CaSO₄:Sm it is 0.1 mol % and for CaSO₄:Dy it is 0.2 mol %. Further, the primary study of the TL response curves for all the three phosphors confirms linearity in the studied dose range (i.e., 30 Gy to 500 Gy). Finally, CaSO₄:Dy was also studied for its energy dependence property which plays an important role in defining the utility of a phosphor for dosimetric applications. The range of doses used for the energy dependence study was from 30 Gy to 500 Gy from Cs-137 (0.662 MeV). The nano-phosphors showed potential to be used as radiation dosimeter in the studied range of gamma radiation and thus must be studied for a wider range of doses.

Keywords: gamma radiation, nanocrystalline, radiation dosimetry, thermoluminescence

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Authors: Mattahias Maj, Fabio Tatzgern, Karl Adam, Damir Kahrimanovic, Markus Varga

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Torpedo ladles are necessary transport carriages in steel production to move the molten crude iron from the blast furnace to the steel refining plant. This requires the ladles to be high temperature resistant and insulate well to preserve the temperature and hold the risk of solidification at bay. Therefore, the involved refractories lining the inside of the torpedo ladles are chosen mostly according to their thermal properties, although wear of the materials by the liquid iron is also of major importance. In this work, we combined investigations of the thermal behaviour with wear studies of the lining over the whole lifetime of a torpedo ladle. Additional numerical simulations enabled a detailed model of the mechanical loads and temperature propagation at the various stations (heating, filling, emptying, cooling). The core of the investigation were detailed 3D measurements of the ladle’s cavity and thereby quantitative information of the wear progress at different time intervals during the lifetime of the ladles. The measurements allowed for a separation of different wear zones according to severity, namely the “splash zone” where the melt directly hits the ladle, the “melt zone” where during transport always liquid melt is present, and the “slag zone”, where the slag floats on the melt causing the most severe wear loss. Numerical simulations of the filling process were taken to calculate stress levels and temperature gradients, which led to the different onset of wear on those zones. Thermal imaging and punctual temperature measurements allowed for a study of the thermal consequences entailed by the wear onset. Additional “classical” damage analysis of the worn refractories complete the investigation. Thereby the wear mechanisms leading to the substantial wear loss were disclosed.

Keywords: high temperature, tribology, liquid-solid interaction, refractories, thermography

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Authors: S. Koul, Joshua Adedamola

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Currently, the global concerning fact about electromagnetic pollution (EMP) is that it not only adversely affects human health but rather projects the malfunctioning of sensitive equipment both locally and at a global level. The market offers many incumbent technologies to solve the issues, but still, a processable sustainable material solution with acceptable limits for GHG emission is still at an exploratory stage. The present work offers a sustainable material solution with a wide range of processability in terms of a polymeric resin matrix and shielding operational efficiency across the electromagnetic spectrum, covering both ionizing and non-ionizing electromagnetic radiations. The present work offers an in-situ synthesized conducting polyaniline (PANI) in the presence of the hybrid dual dopant system with tuned conductivity and high shielding efficiency between 89 to 92 decibels, depending upon the EMI frequency range. The conductive polymer synthesized in the presence of a hybrid dual dopant system via the in-situ emulsion polymerization method offers a higher surface resistance of 1.0 ohms/cm with thermal stability up to 2450C in their powder form. This conductive polymer with a hybrid dual dopant system was used as a filler material with different polymeric thermoplastic resin systems for the preparation of conductive composites. Intrinsically Conductive polymeric (ICP) composites based on hybrid dual dopant systems were prepared using melt blending, extrusion, and finally by, compression molding processing techniques. ICP composites with hybrid dual dopant systems offered good mechanical, thermal, structural, weathering, and stable surface resistivity properties over a period of time. The preliminary shielding behavior for ICP composites between frequency levels of 10 GHz to 24GHZ offered a shielding efficiency of more than 90 dB.

Keywords: ICP, dopant, EMI, shielding

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Authors: Imen Abid, Rachel Calvet, Michel Baltas

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Flavonoids are secondary metabolites that belong to a polyphenolic class, present in fruits and vegetables, playing a significant role in biological systems. The structural variations of these flavonoids are associated with many biological and pharmacological activities (antioxidant, anti-inflammatory, anticancer, antibacterial, antifungal, antiviral, and antimalarial). Given their importance in plants and health-promoting roles in humans, significant efforts have been devoted towards their isolation of flavonoids and chemical elaboration (organic synthesis). But with the increasing public concern over environmental degradation and future resources, it is of great importance for chemists to come up with different approaches, less hazardous to human health and the environment. Being employed in large amounts, the solvents used in organic synthesis are high on the list of environmental pollutants. To overcome these problems, our approach is to develop unconventional processes involving solvent-free conditions. The application of mechanical forces to solvent-free or solvent-less reaction mixtures through the use of ball mills offers many advantages over traditional solvent-based strategies. It is one of the unconventional activation methods, which makes it possible to overcome the use of solvents, in the context of green chemistry and more respectful of the environment.

Keywords: organic synthesis, green chemistry, mecanochemistry, pharmaceutical molecules

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Authors: Da-Wei Wang, Liang Yang, Xuan-Long Peng, Mei-Chuan Kuo, Jen-Taut Yeh

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The tensile retention and waterproof properties of thermoplastic starch (TPS) resins were significantly enhanced by modifying with proper amounts of citric acid (CA) and by melt-blending with poly(lactic acid) (PLA), although no distinguished chemical reaction occurred between CA and starch molecules. As evidenced by Fourier transform infrared spectroscopy and Solid-state 13C Nuclear Magnetic Resonance analyses, disruption of intra and interhydrogen-bondings within starch molecules did occur during the modification processes of CA modified TPS (i.e. TPS100CAx) specimens. The tensile strength (σf) retention values of TPS specimens reduced rapidly from 27.8 to 20.5 and 0.4 MPa, respectively, as the conditioning time at 20°C/50% relative humidity (RH) increased from 0 to 7 and 70 days, respectively. While the elongation at break (εf) retention values of TPS specimens increased rapidly from 5.9 to 6.5 and 34.8%, respectively, as the conditioning time increased from 0 to 7 and 70 days. After conditioning at 20°C/50% RH for 70 days, the σf and εf retention values of the best prepared (TPS100CA0.1)30PLA70 specimen are equivalent to 85% and 167% of its initial σf and εf values, respectively, and are more than 105 times higher but 48% lower than those of TPS specimens conditioned at 20°C/50% RH for the same amount of time. Demarcated diffraction peaks, new melting endotherms of recrystallized starch crystals and distinguished ductile characteristics with drawn debris were found for many conditioned TPS specimens, however, only slight retrogradation effect and much less drawn debris was found for most conditioned TPS100CAx and/or (TPS100CA0.1)xPLAy specimens. The significantly improved water proof, tensile retention properties and relatively unchanged in retrogradation effect found for most conditioned TPS100CAx and/or (TPS100CA0.1)xPLAy specimens are apparently due to the efficient blocking of the moisture-absorbing hydroxyl groups (free or hydrogen bonded) by hydrogen-bonding CA with starch molecules during their modification processes.

Keywords: thermoplastic starch, hydrogen-bonding, water proof, strength retention

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Authors: Sabina Huč, Staffan Svensson, Tomaž Hozjan

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Timber structures may be exposed to various environmental conditions during their service life. Often, the structures have to resist extreme changes in the relative humidity of surrounding air, with simultaneously carrying the loads. Wood material response for this load case is seen as increasing deformation of the timber structure. Relative humidity variations cause moisture changes in timber and consequently shrinkage and swelling of the material. Moisture changes and loads acting together result in mechano-sorptive creep, while sustained load gives viscoelastic creep. In some cases, magnitude of the mechano-sorptive strain can be about five times the elastic strain already at low stress levels. Therefore, analyzing mechano-sorptive creep and its influence on timber structures’ long-term behavior is of high importance. Relatively many one-dimensional rheological models for rheological behavior of wood can be found in literature, while a number of models coupling creep response in each material direction is limited. In this study, mathematical formulation of a coupled two-dimensional mechano-sorptive model and its application to the experimental results are presented. The mechano-sorptive model constitutes of a moisture transport model and a mechanical model. Variation of the moisture content in wood is modelled by multi-Fickian moisture transport model. The model accounts for processes of the bound-water and water-vapor diffusion in wood, that are coupled through sorption hysteresis. Sorption defines a nonlinear relation between moisture content and relative humidity. Multi-Fickian moisture transport model is able to accurately predict unique, non-uniform moisture content field within the timber member over time. Calculated moisture content in timber members is used as an input to the mechanical analysis. In the mechanical analysis, the total strain is assumed to be a sum of the elastic strain, viscoelastic strain, mechano-sorptive strain, and strain due to shrinkage and swelling. Mechano-sorptive response is modelled by so-called spring-dashpot type of a model, that proved to be suitable for describing creep of wood. Mechano-sorptive strain is dependent on change of moisture content. The model includes mechano-sorptive material parameters that have to be calibrated to the experimental results. The calibration is made to the experiments carried out on wooden blocks subjected to uniaxial compressive loaded in tangential direction and varying humidity conditions. The moisture and the mechanical model are implemented in a finite element software. The calibration procedure gives the required, distinctive set of mechano-sorptive material parameters. The analysis shows that mechano-sorptive strain in transverse direction is present, though its magnitude and variation are substantially lower than the mechano-sorptive strain in the direction of loading. The presented mechano-sorptive model enables observing real temporal and spatial distribution of the moisture-induced strains and stresses in timber members. Since the model’s suitability for predicting mechano-sorptive strains is shown and the required material parameters are obtained, a comprehensive advanced analysis of the stress-strain state in timber structures, including connections subjected to constant load and varying humidity is possible.

Keywords: mechanical analysis, mechano-sorptive creep, moisture transport model, timber

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Authors: P. M. Fonseca Alfonso, E. A. Murillo Ruiz, M. Diaz Lagos

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Understanding the physicochemical properties and mineralogy of fly ash from a particular source is essential for to protect the environment and considering its possible applications, specifically, in the production of geopolymeric materials that solidify/stabilize heavy metals ions. The results of the characterization of three fly ash samples are shown in this paper. The samples were produced in the TERMOPAIPA IV thermal power plant in the State of Boyaca, Colombia. The particle size distribution, chemical composition, mineralogy, and molecular structure of three samples were analyzed using laser diffraction, X-ray fluorescence, inductively coupled plasma mass spectrometry, X-ray diffraction, and infrared spectroscopy respectively. The particle size distribution of the three samples probably ranges from 0.128 to 211 μm. Approximately 59 elements have been identified in the three samples. It is noticeable that the ashes are made up of aluminum and silicon compounds. Besides, the iron phase in low content was also found. According to the results found in this study, the fly ash samples type F has a great potential to be used as raw material for the manufacture of geopolymers with potential use in the stabilization/solidification of heavy metals; mainly due to the presence of amorphous aluminosilicates typical of this type of ash, which react effectively with alkali-activator.

Keywords: fly ash, geopolymers, molecular structure, physicochemical properties.

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Authors: P. Raajeswari, S. M. Devatha, R. Pragatheeswari

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The edible packaging is a new trendsetter in the era of modern packaging. The researchers and food scientist recognise edible packaging as a useful alternative or addition to conventional packaging to reduce waste and to create novel applications for improving product stability. Starch was extracted from different sources that contains abundantly like potato, tapioca, rice, wheat, and corn. The starch based edible films and cutleries are developed as an alternative for conventional packages providing the nutritional benefit when consumed along with the food. The development of starch based edible films by the extraction of starch from various raw ingredients at lab scale level. The films are developed by the employment of plasticiser at different concentrations of 1.5ml and 2ml. The films developed using glycerol as a plasticiser in filmogenic solution to increase the flexibility and plasticity of film. It reduces intra and intermolecular forces in starch, and it increases the mobility of starch based edible films. The films developed are tested for its functional properties such as thickness, tensile strength, elongation at break, moisture permeability, moisture content, and puncture strength. The cutleries like spoons and cups are prepared by making dough and rolling the starch along with water. The overall results showed that starch based edible films absorbed less moisture, and they also contributed to the low moisture permeability with high tensile strength. Food colorants extracted from red onion peel, pumpkin, and red amaranth adds on the nutritive value, colour, and attraction when incorporated in edible cutleries, and it doesn’t influence the functional properties. Addition of a low quantity of glycerol in edible films and colour extraction from onion peel, pumpkin, and red amaranth enhances biodegradability and provides a good quantity of nutrients when consumed. Therefore, due to its multiple advantages, food starch can serve as the best response for eco-friendly industrial products aimed to replace single use plastics at low cost.

Keywords: edible films, edible cutleries, plasticizer, glycerol, starch, functional property

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Authors: Vinh Duy Cao, Carlos Salas-Bringas, Anna M. Szczotok, Marianne Hiorth, Anna-Lena Kjøniksen

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The increasing cost of energy supply for the purposes of heating and cooling creates a demand for more energy efficient buildings. Improved construction techniques and enhanced material technology can greatly reduce the energy consumption needed for the buildings. Microencapsulated phase change materials (MPCM) suspensions utilized as heat transfer fluids for energy storage and heat transfer applications provide promising potential solutions. A full understanding of the flow and thermal characteristics of microcapsule suspensions is needed to optimize the design of energy storage systems, in order to reduce the capital cost, system size, and energy consumption. The MPCM suspensions exhibited pseudoplastic and thixotropic behaviour, and significantly improved the thermal performance of the suspensions. Three different models were used to characterize the thixotropic behaviour of the MPCM suspensions: the second-order structural, kinetic model was found to give a better fit to the experimental data than the Weltman and Figoni-Shoemaker models. For all samples, the initial shear stress increased, and the breakdown rate accelerated significantly with increasing concentration. The thermal performance and rheological properties, especially the selection of rheological models, will be useful for developing the applications of microcapsules as heat transfer fluids in thermal energy storage system such as calculation of an optimum MPCM concentration, pumping power requirement, and specific power consumption. The effect of temperature on the shear thinning properties of the samples suggests that some of the phase change material is located outside the capsules, and contributes to agglomeration of the samples.

Keywords: latent heat, microencapsulated phase change materials, pseudoplastic, suspension, thixotropic behaviour

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Authors: Ali Seirafi

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The purpose of this study was to investigate the effect and application of starch nanocrystals on physicochemical and microbial properties in the industrial production of probiotic yogurt. In this study, probiotic yoghurt was manufactured by industrial method with the optimization and control of the technological factors affecting the probabilistic biomass, using probiotic bacteria Lactobacillus acidophilus and Bifidobacterium bifidum with commonly used yogurt primers. Afterwards, the effects of different levels of fat (1.3%, 2.5 and 4%), as well as the effects of various perbiotic compounds include starch nanocrystals (0.5%, 1 and 1.5%), galactolegalosaccharide (0.5% 1 and 1.5%) and fructooligosaccharide (0.5%, 1 and 1.5%) were evaluated. In addition, the effect of packaging (polyethylene and glass) was studied, while the effect of pH changes and final acidity were studied at each stage. In this research, all experiments were performed in 3 replications and the results were analyzed in a completely randomized design with SAS version 9.1 software. The results of this study showed that the addition of starch nanocrystal compounds as well as the use of glass packaging had the most positive effects on the survival of Lactobacillus acidophilus bacteria and the addition of nano-crystals and the increase in the cooling rate of the product, had the most positive effects on the survival of bacteria Bifidobacterium bifidum.

Keywords: Bifidobacterium bifidum, Lactobacillus acidophilus, prebiotics, probiotic yogurt

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Authors: Aymen Laadhari

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During the last decade, an increasing number of contributions have been made in the fields of scientific computing and numerical methodologies applied to the study of the hemodynamics in the heart. In contrast, the numerical aspects concerning the interaction of pulsatile blood flow with highly deformable thin leaflets have been much less explored. This coupled problem remains extremely challenging and numerical difficulties include e.g. the resolution of full Fluid-Structure Interaction problem with large deformations of extremely thin leaflets, substantial mesh deformations, high transvalvular pressure discontinuities, contact between leaflets. Although the Lagrangian description of the structural motion and strain measures is naturally used, many numerical complexities can arise when studying large deformations of thin structures. Eulerian approaches represent a promising alternative to readily model large deformations and handle contact issues. We present a fully Eulerian finite element methodology tailored for the simulation of pulsatile blood flow in the aorta and sinus of Valsalva interacting with highly deformable thin leaflets. Our method enables to use a fluid solver on a fixed mesh, whilst being able to easily model the mechanical properties of the valve. We introduce a semi-implicit time integration scheme based on a consistent NewtonRaphson linearization. A variant of the classical Newton method is introduced and guarantees a third-order convergence. High-fidelity computational geometries are built and simulations are performed under physiological conditions. We address in detail the main features of the proposed method, and we report several experiments with the aim of illustrating its accuracy and efficiency.

Keywords: eulerian, level set, newton, valve

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Authors: Alma Ramić, Mirjana Skočibušić, Renata Odžak, Tomica Hrenar, Ines Primožič

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In an attempt to identify a new class of antimicrobial agents, the antimicrobial potential of Cinchona alkaloid derivatives was evaluated. The bark of the Cinchona trees is the source of a variety of alkaloids, among which the best known are quinine, quinidine, cinchonine and cinchonidine. They are very useful as organocatalysts in stereoselective synthesis. On the other hand, quinine is traditionally used in the treatment of malaria. Furthermore, Cinchona alkaloids possess various analgesic, anti-inflammatory and anti–arrhythmic properties as well. In this work we present the synthesis of twenty quaternary derivatives of pseudo−enantiomeric Cinchona alkaloid derivatives to evaluate their antibacterial activity. Quaternization of quinuclidine moiety was carried out with groups diverse in their size. The structures of compounds were systematically modified to obtain drug-like properties with proper physical and chemical properties and avoiding toxophore. All compounds were prepared in good yields and were characterized by standard analytical spectroscopy methods (1D and 2D NMR, IR, MS). The antibacterial activities of all compounds were evaluated against series of recent clinical isolates of antibiotic susceptible Gram-positive and resistant Gram-negative pathogens by determining their zone of inhibition and minimum inhibitory concentrations. All compounds showed good to strong broad-spectrum activity, equivalent or better in comparison with standard antibiotics used. Furthermore, seven compounds exhibited significant antibacterial efficiency against Gram-negative isolates. To visualize the results, principal component analysis was used as an additional classification tool. Cytotoxicity of compounds with different cell lines in human cell culture was determined. Based on these results, substituted quaternary Cinchona scaffold can be considered as promising new class of antimicrobials and further investigations should be performed. Supported by Croatian Science Foundation, Project No 3775 ADESIRE.

Keywords: antibacterial efficiency, cinchona alkaloids, cytotoxicity, pseudo‐enantiomers

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Authors: Didik Sugiyanto

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Conditions that often occur in the framework of a particular vehicle at a car is a collision or collision with another object, an example of such damage is to the frame or chassis for the required design framework that is able to absorb impact energy. Characteristics of the material are influenced by the value of the stiffness of the material that need to be considered in choosing the material properties of the material. To obtain material properties that can be adapted to the experimental conditions tested the tensile and compression testing. In this study focused on the chassis at an angle of 150, 300, and 450. It is based on field studies that vehicle primarily for freight cars have a point of order light between 150 to 450. Research methods include design tools, design framework, procurement of materials and experimental tools, tool-making, the manufacture of the test framework, and the testing process, experiment is testing the power of the press to know the order. From this test obtained the maximum force on the corner of 150 was 569.76 kg at a distance of 16 mm, angle 300 is 370.3 kg at a distance of 15 mm, angle 450 is 391.71 kg at a distance of 28 mm. After reaching the maximum force the order will occur collapse, followed by a decrease in the next distance. It can be concluded that the greatest strain energy occurs at an angle of 150. So it is known that the frame at an angle of 150 produces the best level of security.

Keywords: buckling, collapse, body frame, vehicle

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Authors: Boutahar Lhoucine, El Bikri Khalid, Benamar Rhali

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In this paper, the non-linear free axisymmetric vibration of a thin annular plate made of functionally graded material (FGM) has been studied by using the energy method and a multimode approach. FGM properties vary continuously as well as non-homogeneity through the thickness direction of the plate. The theoretical model is based on the classical plate theory and the Von Kármán geometrical non-linearity assumptions. An approximation has been adopted in the present work consisting of neglecting the in-plane deformation in the formulation. Hamilton’s principle is used to derive the governing equation of motion. The problem is solved by a numerical iterative procedure in order to obtain more accurate results for vibration amplitudes up to 1.5 times the plate thickness. The numerical results are given for the first axisymmetric non-linear mode shape for a wide range of vibration amplitudes and they are presented either in tabular form or in graphical form to show the effect that the vibration amplitude and the variation in material properties have significant effects on the frequencies and the bending stresses in large amplitude vibration of the functionally graded annular plate.

Keywords: non-linear vibrations, annular plates, large amplitudes, functionally graded material

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Authors: Rabah Bensaha, Badreeddine Toubal

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Un-doped TiO2, Co single doped TiO2 and (Cu-Co) co-doped TiO2 thin films have been growth on silicon substrates by the sol-gel dip coating technique. We mainly investigated both effects of the dopants and annealing temperature on the structural, optical and electrical properties of TiO2 films using X-ray diffraction (XRD), Raman and FTIR spectroscopy, Atomic force microscopy (AFM), Scanning electron microscopy (SEM), UV–Vis spectroscopy. The chemical compositions of Co-doped and (Cu-Co) co-doped TiO2 films were confirmed by XRD, Raman and FTIR studies. The average grain sizes of CoTiO3-TiO2 nanocomposites were increased with annealing temperature. AFM and SEM reveal a completely the various nanostructures of CoTiO3-TiO2 nanocomposites thin films. The films exhibit a high optical reflectance with a large band gap. The highest electrical conductivity was obtained for the (Cu-Co) co-doped TiO2 films. The polyhedral surface morphology might possibly improve the surface contact between particle sizes and then contribute to better electron mobility as well as conductivity. The obtained results suggest that the prepared TiO2 films can be used for optoelectronic applications.

Keywords: sol-gel, TiO2 thin films, CoTiO3-TiO2 nanocomposites films, Electrical conductivity

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Authors: Jelena Filipovic, Milenko Kosutic

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The dynamic way of life has the tendency to simplify and decrease preparing healthy, quick, cheap and safe meals. Spelt pasta is meeting most of these goals. Contrary to bread, pasta can be stored a long time without deterioration in flavour, odour and usability without losing quality. This paper deals with the chemical composition and content of fatty acids in flaxseed and spelt flour. Ratio of essential fatty acids ω-6/ω-3 is also analysed in spelt pasta and pasta with 0%, 10% and 20% flaxseed flour. Gas chromatography with mass spectrometry is used for carrying out a quantitative analysis of flaxseed flour, spelt flour and pasta liposoluble extracts. Flaxseed flour has a better fatty acid profile than spelt flour, with low levels of saturated fat (approximately 9g/100g), high concentration of linolenic acid (57g/100g) and lower content of linoleic acid (16g/100g), as well as superior ω-6/ω-3 ratio that is 1:4. Flaxseed flour in the share of 10% and 20% in spelt pasta positively contributes to the essential fatty acids daily intake recommended by nutritionists and the improvement of ω-6/ω-3 ratio (6,7:1 and 1:1.2). This paper points out that investigated pasta with flaxseed is a new product with improved functional properties due to high level of ω-3 fatty acids and it is acceptable for consumers in regard to sensory properties.

Keywords: flaxseed, spelt, fatty acids, ω-3/ω-6 ratio, pasta

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Authors: Pankaj Pathak, Susmita Sharma

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Incessant industrial growth fulfill the energy demand of present day society, at the same time it produces huge amount of waste which could be hazardous or non-hazardous in nature. These wastes are coming out from different sources viz, nuclear power, thermal power, coal mines which contain different types of contaminants and one of the emergent contaminant is strontium, used in the present study. The isotope of strontium (Sr90) is radioactive in nature with half-life of 28.8 years and permissible limit of strontium in drinking water is 1.5 ppm. Above the permissible limit causes several types of diseases in human being. Therefore, safe disposal of strontium into ground becomes a biggest challenge for the researchers. In this context, bentonite is being used as an efficient material to retain strontium onto ground due to its specific physical, chemical and mineralogical properties which exhibits higher cation exchange capacity and specific surface area. These properties influence the interaction between strontium and bentonite, which is quantified by employing a parameter known as distribution coefficient. Batch test was conducted, and sorption isotherms were modelled at different interaction time. The pseudo first-order and pseudo second order kinetic models have been used to fit experimental data, which helps to determine the sorption rate and mechanism.

Keywords: bentonite, interaction time, sorption, strontium

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Authors: Rebecca Thombre, Aishwarya Borate

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Chemical synthesis of nanoparticles produces toxic by-products, as a result of which eco-friendly methods of synthesis are gaining importance. The synthesis of nanoparticles using plant derived extracts is economical, safe and eco-friendly. Biostabilized gold nanoparticles were synthesized using extracts of Garcinia indica. The gold nanoparticles were characterized using UV-Vis spectrophotometry and demonstrated a peak at 527 nm. The presence of plant derived peptides and phytoconstituents was confirmed using the FTIR spectra. TEM analysis revealed formation of gold nanopyramids and nanorods. The SAED analysis confirmed the crystalline nature of nanoparticles. The gold nanoparticles demonstrated antibacterial and antifungal activity against Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Aspergillus niger and Pichia pastoris. The cytotoxic activity of gold nanoparticles was studied using HEK, Hela and L929 cancerous cell lines and the apoptosis of cancerous cells were observed using propidium iodide staining. Thus, a simple and eco-friendly method for synthesis of biostabilized gold nanoparticles using fruit extracts of Garcinia indica was developed and the nanoparticles had potent antibacterial, antifungal and anticancer properties.

Keywords: cytotoxic, gold nanoparticles, green synthesis, Garcinia indica, anticancer

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Authors: Kyong-Ku Yun, Seung-Yeon Han, Kyeo-Re Lee

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Silica fume which is a super-fine byproduct of ferrosilicon or silicon metal has a filling effect on micro-air voids or a transition zone in a hardened cement paste by appropriate mixing, placement, and curing. It, also, has a Pozzolan reaction which enhances the interior density of the hydrated cement paste through a formation of calcium silicate hydroxide. When substituting cement with silica fume, it improves water tightness and durability by filling effect and Pozzolan reaction. However, it needs high range water reducer or super-plasticizer to distribute silica fume into a concrete because of its finesses and high specific surface area. In order to distribute into concrete evenly, cement manufacturers make a pre-blended cement of silica fume and provide to a market. However, a special mixing procedures and another transportation charge another cost and this result in a high price of pre-blended cement of silica fume. The purpose of this dissertation was to investigate the dispersion of silica fume by air slurry and its effect on the mechanical properties of at ready-mixed concrete. The results are as follows: A dispersion effect of silica fume was measured from an analysis of standard deviation for compressive strength test results. It showed that the standard deviation decreased as the air bubble content increased, which means that the dispersion became better as the air bubble content increased. The test result of rapid chloride permeability test showed that permeability resistance increased as the percentages of silica fume increased, but the permeability resistance decreased as the quantity of mixing air bubble increased. The image analysis showed that a spacing factor decreased and a specific surface area increased as the quantity of mixing air bubble increased.

Keywords: cellular sprayed concrete, silica fume, deviation, permeability

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Authors: Sampada Katekar, Namdeo Hedaoo

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Cold Bituminous Emulsion Mixtures (CBEMs) are generally produced by mixing unheated aggregate, binder and filler at ambient temperature. Cold bituminous emulsion mixtures have several environmental and cost-effective benefits. But CBEMs offer poor early life properties too and they require long curing time to achieve maximum strength. The main focus of this study is to overcome inferiority of CBEMs by incorporating Rice Husk Ash (RHA) and Ordinary Portland Cement (OPC). In this study, RHA and OPC are substituted for conventional mineral filler in an increased percentage from 0 to 3% with an increment of 1%. Marshall stability, retained stability and tensile strength tests were conducted to evaluate the enhancement in performance of CBEMs. The experimental results have shown that Marshall stability and tensile strength of CBEMs increased significantly by replacing the conventional mineral filler with RHA and OPC. The addition of RHA and OPC in CBEMs result in a reduction in moisture induced damages. However, stability and tensile strength values of RHA modified CBEMs are higher than that of OPC modified CBEMs.

Keywords: cold bituminous emulsion mixtures, Marshall stability test, ordinary Portland cement, rice husk ash

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Authors: Sadman Durlov, Aditya Ganesh-Ram, Hamidreza Hekmatjou, Md Najmus Salehin, Nora Shayesteh Ameri

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In the field of additive manufacturing, tungsten stands out for its exceptional resistance to high temperatures, making it an ideal candidate for use in extreme conditions. However, its inherent brittleness and vulnerability to thermal cracking pose significant challenges to its manufacturability. This study explores the microstructural evolution of tungsten processed through layer-wise rolling in laser powder bed fusion additive manufacturing, utilizing a comprehensive approach that combines advanced simulation techniques with empirical research. We aim to uncover the complex processes of plastic deformation and microstructural transformations, with a particular focus on the dynamics of grain size, boundary evolution, and phase distribution. Our methodology employs a combination of simulation and experimental data, allowing for a detailed comparison that elucidates the key mechanisms influencing microstructural alterations during the rolling process. This approach facilitates a deeper understanding of the material's behavior under additive manufacturing conditions, specifically in terms of deformation and recrystallization. The insights derived from this research not only deepen our theoretical knowledge but also provide actionable strategies for refining manufacturing parameters to improve the tungsten components' mechanical properties and functional performance. By integrating simulation with practical experimentation, this study significantly enhances the field of materials science, offering a robust framework for the development of durable materials suited for challenging operational environments. Our findings pave the way for optimizing additive manufacturing techniques and expanding the use of tungsten across various demanding sectors.

Keywords: additive manufacturing, layer wise rolling, refractory materials, in-situ microstructure modifications

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Authors: Jae-Yong Park, Yeo-Kyeong Lee, Hee-Sun Kim

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Purpose: This study aims at investigating the mechanical behaviors of mastication, according to various teeth movement. There are three masticatory cases which are general case and 2 cases of teeth movement. General case includes the common arrange of all teeth and 2 cases of teeth movement are that one is the half movement location case of molar teeth in no. 14 tooth seat after extraction of no. 14 tooth and the other is no. 14 tooth seat location case of molar teeth after extraction in the same case before. Materials and Methods: In order to analyze these cases, 3 dimensional finite element (FE) model of the skull were generated based on computed tomography images, 964 dicom files of 38 year old male having normal occlusion status. An FE model in general occlusal case was used to develop CAE procedure. This procedure was applied to FE models in other occlusal cases. The displacement controls according to loading condition were applied effectively to simulate occlusal behaviors in all cases. From the FE analyses, von Mises stress distribution of skull and teeth was observed. The von Mises stress, effective stress, had been widely used to determine the absolute stress value, regardless of stress direction and yield characteristics of materials. Results: High stress was distributed over the periodontal area of mandible under molar teeth when the mandible was transmitted to the coronal-apical direction in the general occlusal case. According to the stress propagation from teeth to cranium, stress distribution decreased as the distribution propagated from molar teeth to infratemporal crest of the greater wing of the sphenoid bone and lateral pterygoid plate in general case. In 2 cases of teeth movement, there were observed that high stresses were distributed over the periodontal area of mandible under teeth where they are located under the moved molar teeth in cranium. Conclusion: The predictions of the mechanical behaviors of general case and 2 cases of teeth movement during the masticatory process were investigated including qualitative validation. The displacement controls as the loading condition were applied effectively to simulate occlusal behaviors in 2 cases of teeth movement of molar teeth.

Keywords: cranium, finite element analysis, mandible, masticatory action, occlusal force

Procedia PDF Downloads 386

Authors: Milica Carević, Katarina Banjanac, Marija ĆOrović, Ana Milivojević, Nevena Prlainović, Aleksandar Marinković, Dejan Bezbradica

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Nowadays, considering the growing awareness of functional food beneficial effects on human health, due attention is dedicated to the research in the field of obtaining new prominent products exhibiting improved physiological and physicochemical characteristics. Therefore, different approaches to valuable bioactive compounds synthesis have been proposed. β-Galactosidase, for example, although mainly utilized as hydrolytic enzyme, proved to be a promising tool for these purposes. Namely, under the particular conditions, such as high lactose concentration, elevated temperatures and low water activities, reaction of galactose moiety transfer to free hydroxyl group of the alternative acceptor (e.g. different sugars, alcohols or aromatic compounds) can generate a wide range of potentially interesting products. Up to now, galacto-oligosaccharides and lactulose have attracted the most attention due to their inherent prebiotic properties. The goal of this study was to obtain a novel product sorbitol galactoside, using the similar reaction mechanism, namely transgalactosylation reaction catalyzed by β-galactosidase from Aspergillus oryzae. By using sugar alcohol (sorbitol) as alternative acceptor, a diverse mixture of potential prebiotics is produced, enabling its more favorable functional features. Nevertheless, an introduction of alternative acceptor into the reaction mixture contributed to the complexity of reaction scheme, since several potential reaction pathways were introduced. Therefore, the thorough optimization using response surface method (RSM), in order to get an insight into different parameter (lactose concentration, sorbitol to lactose molar ratio, enzyme concentration, NaCl concentration and reaction time) influences, as well as their mutual interactions on product yield and productivity, was performed. In view of product yield maximization, the obtained model predicted optimal lactose concentration 500 mM, the molar ratio of sobitol to lactose 9, enzyme concentration 0.76 mg/ml, concentration of NaCl 0.8M, and the reaction time 7h. From the aspect of productivity, the optimum substrate molar ratio was found to be 1, while the values for other factors coincide. In order to additionally, improve enzyme efficiency and enable its reuse and potential continual application, immobilization of β-galactosidase onto tailored silica nanoparticles was performed. These non-porous fumed silica nanoparticles (FNS)were chosen on the basis of their biocompatibility and non-toxicity, as well as their advantageous mechanical and hydrodinamical properties. However, in order to achieve better compatibility between enzymes and the carrier, modifications of the silica surface using amino functional organosilane (3-aminopropyltrimethoxysilane, APTMS) were made. Obtained support with amino functional groups (AFNS) enabled high enzyme loadings and, more importantly, extremely high expressed activities, approximately 230 mg proteins/g and 2100 IU/g, respectively. Moreover, this immobilized preparation showed high affinity towards sorbitol galactoside synthesis. Therefore, the findings of this study could provided a valuable contribution to the efficient production of physiologically active galactosides in immobilized enzyme reactors.

Keywords: β-galactosidase, immobilization, silica nanoparticles, transgalactosylation

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Authors: Aruma Baduge Kithma Hansanee De Silva

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Haskap (Lonicera caerulea L.), also known as blue honeysuckle, is a recently commercialized berry crop in Canada. Haskap berries are rich in polyphenols, including anthocyanins, which are known for potential health-promoting effects. Cyanidin-3-O-glucoside (C3G) is the most prominent anthocyanin of haskap berries. Recent literature reveals the efficacy of C3G in reducing the risk of type 2 diabetes (T2D), which has become an increasingly common health issue around the world. The T2D is characterized as a metabolic disorder of hyperglycemia and insulin resistance. It has been demonstrated that C3G has anti-diabetic effects in various ways, including improvement in insulin sensitivity, and inhibition of activities of carbohydrate-hydrolyzing enzymes, including alpha-amylase and alpha-glucosidase. The goal of this study was to investigate the influence of variety and harvesting date on haskap composition, biological properties, and antidiabetic properties. The polyphenolic compounds present in four commercially grown haskap cultivars, Aurora, Rebecca, Larissa and Evie among five harvesting stages (H1-H5), were extracted separately in 80% ethanol and analyzed to characterize their phenolic profiles. The haskap berries contain different types of polyphenols including flavonoids and phenolic acids. Anthocyanin is the major type of flavonoid. C3G is the most prominent type of anthocyanin, which accounts for 79% of total anthocyanin in all extracts. The variety Larissa at H5 contained the highest average C3G content, and its ethanol extract had the highest (1212.3±63.9 mg/100g FW) while, Evie at H1 contained the lowest C3G content (96.9±40.4 mg/100g FW). The average C3G content of Larissa from H1 – H5 varies from 208 – 1212 mg/100g FW. Quarcetin-3-Rutinoside (Q3Rut) is the major type of flavonol and highest is observed in Rebecca at H4 (47.81 mg/100g FW). The haskap berries also contained phenolic acids, but approximately 95% of the phenolic acids consisted of chlorogenic acid. The cultivar Larissa has a higher level of anthocyanin than the other four cultivars. The highest total phenolic content is observed in Evie at H5 (2.97±1.03 mg/g DW) while the lowest in Rebecca at H1 (1.47±0.96 mg/g DW). The antioxidant capacity of Evie at H5 was higher (14.40±2.21 µmol TE/ g DW) among other cultivars and the lowest observed in Aurora at H3 (5.69±0.34 µmol TE/ g DW). Furthermore, Larissa H5 shows the greatest inhibition of carbohydrate-hydrolyzing enzymes including alpha-glucosidase and alpha-amylase. In conclusion Larissa, at H5 demonstrated highest polyphenol composition and antidiabetic properties.

Keywords: anthocyanin, cyanidin-3-O-glucoside, haskap, type 2 diabetes

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Authors: T. P. Sathishkumar, P. Navaneethakrishnan

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The research work investigates the variation of tensile properties for the sansevieria ehrenbergii fiber (SEF) and SEF reinforced polyester composites respect to various water absorption time. The experiments were conducted according to ATSM D3379-75 and ASTM D570 standards. The percentage of water absorption for composite specimens was measured according to ASTM D570 standard. The fiber of SE was cut in to 30 mm length for preparation of the composites. The simple hand lay-up method followed by compression moulding process adopted to prepare the randomly oriented SEF reinforced polyester composites at constant fiber weight fraction of 40%. The surface treatment was done on the SEFs with various chemicals such as NaOH, KMnO4, Benzoyl Peroxide, Benzoyl Chloride and Stearic Acid before preparing the composites. NaOH was used for pre-treatment of all other chemical treatments. The morphology of the tensile fractured specimens studied using the Scanning Electron Microscopic. The tensile strength of the SEF and SEF reinforced polymer composites were carried out with various water absorption time such as 4, 8, 12, 16, 20 and 24 hours respectively. The result shows that the tensile strength was drop off with increase in water absorption time for all composites. The highest tensile property of raw fiber was found due to lowest moistures content. Also the chemical bond between the cellulose and cementic materials such as lignin and wax was highest due to lowest moisture content. Tensile load was lowest and elongation was highest for the water absorbed fibers at various water absorption time ranges. During this process, the fiber cellulose inhales the water and expands the primary and secondary fibers walls. This increases the moisture content in the fibers. Ultimately this increases the hydrogen cation and the hydroxide anion from the water. In tensile testing, the water absorbed fibers shows highest elongation by stretching of expanded cellulose walls and the bonding strength between the fiber cellulose is low. The load carrying capability was stable at 20 hours of water absorption time. This could be directly affecting the interfacial bonding between the fiber/matrix and composite strength. The chemically treated fibers carry higher load and lower elongation which is due to removal of lignin, hemicellulose and wax content. The water time absorption decreases the tensile strength of the composites. The chemically SEF reinforced composites shows highest tensile strength compared to untreated SEF reinforced composites. This was due to highest bonding area between the fiber/matrix. This was proven in the morphology at the fracture zone of the composites. The intra-fiber debonding was occurred by water capsulation in the fiber cellulose. Among all, the tensile strength was found to be highest for KMnO4 treated SEF reinforced composite compared to other composites. This was due to better interfacial bonding between the fiber-matrix compared to other treated fiber composites. The percentage of water absorption of composites increased with time of water absorption. The percentage weight gain of chemically treated SEF composites at 4 hours to zero water absorption are 9, 9, 10, 10.8 and 9.5 for NaOH, BP, BC, KMnO4 and SA respectively. The percentage weight gain of chemically treated SEF composites at 24 hours to zero water absorption 5.2, 7.3, 12.5, 16.7 and 13.5 for NaOH, BP, BC, KMnO4 and SA respectively. Hence the lowest weight gain was found for KMnO4 treated SEF composites by highest percentage with lowest water uptake. However the chemically treated SEF reinforced composites is possible materials for automotive application like body panels, bumpers and interior parts, and household application like tables and racks etc.

Keywords: fibres, polymer-matrix composites (PMCs), mechanical properties, scanning electron microscopy (SEM)

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Authors: Abdullah Alnutayfat, Alexander Sutin

Abstract:

One of the most important types of renewable energy resources is wind energy which can be produced by wind turbines. The blades of the wind turbine are exposed to the pressure of the harsh environment, which causes a significant issue for the wind power industry in terms of the maintenance cost and failure of blades. One of the reliable methods for blade inspection is the vibroacoustic structural health monitoring (SHM) method which examines information obtained from the structural vibrations of the blade. However, all vibroacoustic SHM techniques are based on comparing the structural vibration of intact and damaged structures, which places a practical limit on their use. Methods for nonlinear vibroacoustic SHM are more sensitive to damage and cracking and do not need to be compared to data from the intact structure. This paper presents the Vibro-Acoustic Modulation (VAM) method based on the modulation of high-frequency (probe wave) by low-frequency loads (pump wave) produced by the blade rotation. The blade rotation alternates bending stress due to gravity, leading to crack size variations and variations in the blade resonance frequency. This method can be used with the classical SHM vibration method in which the blade is excited by piezoceramic actuator patches bonded to the blade and receives the vibration response from another piezoceramic sensor. The VAM modification of this method analyzes the spectra of the detected signal and their sideband components. We suggest the VAM model as the simple mechanical oscillator, where the parameters of the oscillator (resonance frequency and damping) are varied due to low-frequency blade rotation. This model uses the blade vibration parameters and crack influence on the blade resonance properties from previous research papers to predict the modulation index (MI).

Keywords: wind turbine blades, damaged detection, vibro-acoustic structural health monitoring, vibro-acoustic modulation

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