Key Engineering Materials Vol. 928

Abstract: The research on the nanofluid as an alternative transformer oil has been widely attracted the concern of many researchers as the effectiveness as insulation and cooling agent of the existing transformer oil is not achieved satisfactory to accommodate the rising demand of high voltage rate. In this study, nanofluid with a nanomaterial, Carbon Nanotube (CNT), with and without Polyvinylpyrrolidone (PVP) has been formulated, and their AC breakdown voltage of the mineral oil (MO) according to IEC 60156 standard has been characterized. The concentration of CNT study is 0.005, 0.01, 0.015 and 0.02 g/L. It is found that the optimum concentration in nanofluids without PVP is 0.005g/L of nanofluids concentration with the highest breakdown voltage 53.52. In comparison, the highest breakdown voltage for nanofluids with PVP is 33.4kV at 0.01g/L. The existence of PVP in the nanofluids seems not significantly affect the dielectric performance of the degradation of the nanofluid from 5% to 43%. Hence, nanofluids with CNT addition are proofed as a good additive in insulation oil for future transformer applications.

Abstract: A bioplastic fertilizer (BpF) from carboxymethyl cellulose (CMC)/N-P-K/Zeolite composite has been successfully synthesized at the various amounts of zeolite using extrusion techniques (Twin-screw Extruder). The zeolites content was varied at 0.01, 0.1, 0.5, and 1 (wt.% to CMC). The temperature and screw speed were kept at 100 °C and 600 rpm. The ingredients of the composite are mixed with 100% water added to the total mass. A BpF composites and prepared materials were characterized by FT-IR, XRD, and UTM (Universal testing machine). Also, the swelling ratio and stability in water behavior of the composites was evaluated. The result showed that the addition of zeolite increased their tensile strength, decreased the swelling ratio, and has a good stability in water for 30 days. The release of N and P nutrients form composite followed the pseudo second-order kinetic models, while the release K followed the Korsmeyer-Peppas kinetic models. The release of N-P-K from CMC/N-P-K/Zeolite (1 wt.%) composite has followed the standards of the Committee of European Normalization (CEN) and this formulation is potentially to be used in agriculture as a slow-release fertilizer.

Abstract: Nitrogen-based fertilizers are widely consumed to increase productivity since they play an essential role in plant growth. Common commercial fertilizers contain “mobile” nitrogens that can be easily transformed into other nitrogen compounds. The approach method to decrease nitrogen loss is called controlled-release fertilizer (CRF), which is done by modifying fertilizers with coating inhibitors such as polyurethane to provide surface resistance that inhibits nutrient release. Multilayer coating is one of the alternatives to minimize the risk of losing nitrogen content from granular fertilizer. This research will focus on the study of nitrogen release on the CRF modified by various polyurethane coating concentrations (6%, 8%, and 10%). The study was conducted by planting maize plants in a pot inside a greenhouse for nine weeks, followed by a nitrogen release test using a percolator. The morphology of final coating products was observed with scanning electron microscopy, while the mechanical properties and water content were measured with crushing strength test and water stability test. Three weeks after testing, polyurethane can reduce above 60% nitrogen release compared to uncoated fertilizer. After nine weeks since the maizes were planted, the nitrogen release will compare between inside the percolators’ simulation chambers and pot test to see the effect of polyurethane composition with nitrogen release pattern. The results show that the effective composition of polyurethane in CRF products is maximum at 8%^w/_w with nitrogen released above 75%. Keywords: controlled-release fertilizer, polyurethane multilayer coating, nitrogen release

Abstract: Chicken meat has a high nutritional content that makes its freshness rapidly deteriorates. A color change characterized the degradation. Color changes could influence the consumer perception toward food quality. Human perception and evaluation of color are often subjective. Sensors can provide better detection accuracy toward this phenomenon than the human senses. This study aims to determine the change of color attribute of chicken breast meat kinetically and classify meat quality based on color changes during meat storage using Principal Component Analysis (PCA). The experiment was performed with equipment consisting of a Raspberry Pi, Arduino, and a TCS 3200 color sensor. The meat sample was stored in a dark-colored container along with the sensor for 24 hours storage at room temperature. The measurement was done every hour in three replications. Color data from sensor readings in the frequency form was then converted into RGB (Red, Green, Blue) values and finally to L*, a*, b* values during the experiment. The data obtained was sent to the database for kinetic analysis and quality classification using PCA. It was found that the change of color attribute of Chroma (C), Hue Angle (Ho), Color Difference with True Red (DE), and Color Difference (AE) followed zero-order or first-order kinetics reactions. While from the PCA resulted, two chicken meat quality classes, PC 1, explained 85.4%, and PC 2 explained 12.5%.

Abstract: A detailed study on the structural and dielectric characterization of the Nd doped SrTiO₃ ceramics at radio frequencies were conducted in this paper. Sr_1-xNd_xTiO₃ (x from 0 to 0.13) ceramics were synthesized using the conventional solid state ceramic route and the phase purity was confirmed through XRD analysis. XRD patterns of the ceramics showed almost similar peaks with no additional phases. A reduction in the lattice parameter can be observed with increase in the Nd content, which can be attributed to the possible lattice shrinkage due to the substitution by a smaller sized ion. The SEM images also showed a reduction in grain size which can be due the fact that Nd doping induces Sr and Ti vacancies in the system which inhibits the grain growth. The dielectric characterization at 1 MHz was done and optimal values of ε_r=5496 and tanδ=0.0925 were observed at x=0.1. Thus the synthesized ceramics can be used for energy storage applications.

Abstract: Functionally graded materials (FGM) are often an integral part these days in many engineering applications, such as, nuclear structural components, spacecraft and marine structures, thermal barrier coatings used for military applications, etc. These structures are also susceptible to dynamic loads varying from harmonic to impulse type of loadings which are in the form of rotating engines, sudden blasts and others. These loadings often pose serious threats to the structural systems by inflicting fatigue damages or by driving the system in tune with its resonating frequency that eventually lead to the complete collapse of the structure. Therefore, a vibration control strategy needs to be devised to protect these structures from unwanted vibrations due to the external loading. A passive vibration control strategy is proposed in the present research work to control the vibration response of a flat panel made of functionally graded material. At first, the FG plate is numerically modelled using the finite element (FE) method to calculate its response due to a point harmonic force. Ceramic (Alumina) is used for the top part of the FG plate while the bottom is made of metal (Aluminium) and the material property is smoothly varied from ceramic to metal using the power law distribution. Then, several resonators consisting of spring-mass system and parallel to each other are attached to both sides of the panel to isolate the response in the resonating frequency ranges. The FE model for the FG plate with resonator is developed and the controlled vibration response is obtained. The controlled response indicates that the resonators are efficient to produce band-gaps in the resonating frequency regime compared to the bare FG plate.

Abstract: Study of smart functionally graded (FG) beam made of carbon nanotube (CNT) reinforced composites combined with piezoelectric material is carried out. Material parameters of the beam are supposed to vary along its thickness following extended rule of mixture. Finite element model is developed for the functionally graded CNT reinforced beam combined with piezoelectric material using ANSYS software. Numerical results are evaluated using different boundary conditions. Computed results revealed that piezoelectric layer of smart FG beam efficiently controls the bending deformations of the presently studied smart CNT reinforced functionally graded beams. Results are also presented considering various material profiles for the grading of FG beams. It is observed that X type profile distribution considering CNT volume fraction of 0.28 provides minimum bending deflection of the presently studied smart FGCNT reinforced composite beams for the activated as well as inactivated piezoelectric material

Abstract: Tungsten Sulfide (WS₂) has been appeared as visible range semi-conductors with having substantial direct band gap. In two-dimensional (2D) transition metal dichalcogenides (TMDC) i.e.WS₂ has been growing research attention over more than the past twenty years in low cost, energy-efficient, adaptable or environment-friendly material, which is crucial part of optoelectronic emission devices. WS₂ semiconductor thin films were grown on glass and Si substrates by using DC sputtering method. During deposition the substrate were kept at temperature of 200°C. The thin films were studied by X-ray diffraction, UV-Vis spectrometry and Spectrofluorometer (FS5). XRD analysis revealed the nature of grown film effected by temperature of substrate results in to be amorphous. Photoluminescence analysis at 532nm and optical study proved the direct to indirect band transition in WS₂.

Abstract: In this research study, aluminum Nitride (AlN) thin film co-doped with erbium and ytterbium has been deposited on Si (100) substrate by RF magnetron Sputtering. After deposition, the film was annealed at 1100 °C in ambient conditions. It’s structural properties were investigated X-ray diffraction (XRD). Thin films morphology is studied using SEM, and EDX provides the chemical composition information. The photoluminescence property of deposited film was investigated by FS5 spectrofluorometer. XRD result revealed that the film has grown along the c-axis oriented in hexagonal wurtzite structure. SEM Result shows that the average size of the particle is 100 nm. The up-conversion luminescence showed intense green and red emission peaks at 530 nm, 552 nm, and 665 nm due to the transition of Er (²H_11/2 → ⁴I_15/2, ⁴S_3/2 → ⁴I_15/2, and ⁴F_9/2 → ⁴I_15/2) with excitation of 984 nm. The excitation wavelength with 483 nm photons produces visible luminescence in the green and red region with 557 and 660 nm due to Erbium.

Abstract: Multiwall carbon nanotubes (MWCNTs) have recently attracted much attention due to their appealing properties in several domains. Multiwall carbon nanotubes (MWCNTs) were functionalized in this research study and then decorated with silver nanoparticles. Fourier transform Infrared Spectroscopy (FTIR) was used to check the successful attachment of hydroxyl (OH) and carboxyl (C=O) groups with MWCNTs. XRD analysis was used to check the crystallite size of silver nanoparticles and the decoration of silver nanoparticles on MWCNTs. Pure Carbon nanotubes (CNTs) show luminescence in an infrared region having approximately 1.3 eV absorption band. At room temperature, our hybrid material's photoluminescence (PL) spectra indicate only one peak in the UV region and many high-intensity peaks in the visible region. These PL results show the change in the band structure of Ag/MWCNTs composite compared to pure silver nanoparticles and carbon nanotubes. Therefore, it unlocks the possibilities to use this hybrid material for bio-sensing and bio-imaging devices, chemical sensing devices, optoelectronics devices, drug delivery devices, cancer cell detection, and environment detection devices.