Now showing 1 - 6 of 6
  • Publication
    Experimental analysis using thermocouple and infrared thermography of the temperature evolution of lithium-ion polymer cells at different charging rates
    (Springer, 2025)
    A. I. A. Sabandi
    ;
    ;
    M. F. H. Rani
    ;
    N. Maruyama
    ;
    W. K. Wan
    ;
    ; ;
    An experiment was designed to investigate the temperature revolution of lithium-ion polymer (LiPo) cells using two different approaches, thermocouples and infrared thermography. The cells were charged under controlled conditions at rates of 2.0 A, 4.0 A, 6.0 A, 8.0 A, and 10.0 A. The analysis focused on the maximum surface temperature, temperature changes over time, and surface temperature distribution. The findings revealed that higher charging rates result in increased heat generation, causing greater temperature rises, steeper temperature gradients, and higher maximum temperatures. During the charging process, the study also observed endothermic behavior and uneven temperature distribution across the cells. However, upon completing the charging, the surface temperature became evenly distributed without any critical hotspots. Notably, maximum temperatures were observed in the lower regions of the cells for lower charging rates (2.0 A, 4.0 A, and 6.0 A) and in the upper regions for higher rates (8.0 A and 10.0 A). Additionally, infrared thermography provided a clearer and more precise method for measuring surface temperatures compared to thermocouples, as indicated by experimental uncertainty analysis. IR imaging also showed a faster temperature increase at higher charging rates, offering deeper insights into the thermal characteristics of LiPo cells.
  • Publication
    Effect of pineapple leaf (PALF), napier, and hemp fibres as filler on the scratch resistance of epoxy composites
    This article presents the effects of pineapple leaf (PALF), napier, and hemp fibres as filler on the scratch resistance of epoxy composites. In particular, it explores the effect of these natural fillers on the horizontal load, coefficient of friction (COF), penetration depth, fracture toughness, scratch hardness, brittleness index and scratch observation. The mixing method using magnetic stirrer was used to produce the natural fibre-filled epoxy composites with different wt%, namely, 5, 7.5, and 10 wt%. The test was performed using a CSM Revetest Xpress, which consisted of a cone of the half-apex angle of 60° ending with a sphere having a tip radius of 200 μm. The indenter scratch distance and speed were 7 mm and 1.5 mm/min, respectively. The results show that the napier fibre-filled epoxy composites have the highest peak load and COF. It was also noted that the napier fibre-filled epoxy composites have the lowest penetration depth for each wt% of filler. Lastly, the fracture toughness (Kc) for the napier fibre-filled epoxy composites with 10 wt% of filler yielded the highest value of 4.33 MPa.m1/2. It can also be seen that using a scanning electron microscope (SEM), the amount of debris increased with higher of wt% of the natural fibre fillers in the composites. Hence it was demonstrated that the napier fibre-filled epoxy composites have higher scratch resistance compared to the PALF and hemp fibre-filled epoxy composites. Keywords: Surface analysis, Fracture toughness, Scratch resistance, PALF, Napier, Hemp fibres.
      12  19
  • Publication
    Lumped-element circuit modeling for composite scaffold with nano-hydroxyapatite and wangi rice starch
    Mechanistic studies of the interaction of electromagnetic (EM) fields with biomaterials has motivated a growing need for accurate models to describe the EM behavior of biomaterials exposed to these fields. In this paper, biodegradable bone scaffolds were fabricated using Wangi rice starch and nano-hydroxyapatite (nHA). The effects of porosity and composition on the fabricated scaffold were discussed via electrical impedance spectroscopy analysis. The fabricated scaffold was subjected to an electromagnetic field within the X-band and Ku-band (microwave spectrum) during impedance/dielectric measurement. The impedance spectra were analyzed with lumped-element models. The impedance spectra of the scaffold can be embodied in equivalent circuit models composed of passive components of the circuit, i.e., resistors, inductors and capacitors. It represents the morphological, structural and chemical characteristics of the bone scaffold. The developed models describe the impedance characteristics of plant tissue. In this study, it was found that the ε′ and ε″ of scaffold composites exhibited up and down trends over frequencies for both X-band and Ku-band. The circuit models presented the lowest mean percentage errors of Z′ and Z″, i.e., 3.60% and 13.80%, respectively.
      21  1
  • Publication
    Microwave dielectric analysis on adhesive disbond in acrylic glass (Poly (Methyl Methacrylate)) at KU-band
    A microwave dielectric spectroscopy for detecting adhesive disbonds between acrylic glass (aka Poly (methyl methacrylate)) was discussed. The adhesive bond was developed using epoxy resin and acrylate. The level of joint disbond can be quantified using Young Modulus. In this work, the strength of bond is affected by radius of air void within adhesive bond. A high-frequency electromagnetic wave propagated through two joint acrylic glass with acrylate and epoxy adhesive using waveguide adaptor WR90 in conjunction with professional network analyser. This electromagnetic wave is reflected and transmitted at the bond interface due to mismatch impedance at adhesive bond. The output is a dielectric properties that characterizes the bond interface. The increment of Young Modulus leads to increment of dielectric constant and loss factor for epoxy resin and acrylates, respectively.
      7  37
  • Publication
    Lumped-element circuit modeling for composite scaffold with Nano-Hydroxyapatite and wangi rice starch
    Mechanistic studies of the interaction of electromagnetic (EM) fields with biomaterials has motivated a growing need for accurate models to describe the EM behavior of biomaterials exposed to these fields. In this paper, biodegradable bone scaffolds were fabricated using Wangi rice starch and nano-hydroxyapatite (nHA). The effects of porosity and composition on the fabricated scaffold were discussed via electrical impedance spectroscopy analysis. The fabricated scaffold was subjected to an electromagnetic field within the X-band and Ku-band (microwave spectrum) during impedance/dielectric measurement. The impedance spectra were analyzed with lumped-element models. The impedance spectra of the scaffold can be embodied in equivalent circuit models composed of passive components of the circuit, i.e., resistors, inductors and capacitors. It represents the morphological, structural and chemical characteristics of the bone scaffold. The developed models describe the impedance characteristics of plant tissue. In this study, it was found that the ε′ and ε″ of scaffold composites exhibited up and down trends over frequencies for both X-band and Ku-band. The circuit models presented the lowest mean percentage errors of Z′ and Z″, i.e., 3.60% and 13.80%, respectively.
      15  1
  • Publication
    Fabrication and characterization of three-dimensional porous cornstarch/n-HAp biocomposite scaffold
    The aim of this study is to investigate the morphological, functional group, crystallinity and mechanical properties of a three-dimensional porous cornstarch/n-HAp (nano-hydroxyapatite) biocomposite scaffold. In this study, cornstarch/n-HAp scaffolds were fabricated using the solvent casting and particulate leaching technique. The porous cornstarch/n-HAp composites with various cornstarch contents (30, 40, 50, 60, 70, 80 and 90 wt%) were prepared and characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffractometer and compression test. The morphology of the scaffolds possessed macropores (200–600 Î¼m) and micropores (50–100 Î¼m) with a high interconnectivity. The porosity of the porous cornstarch/n-HAp scaffolds varied between 53 and 70% with compressive strength and compressive modulus of 2.03 and 8.27 MPa, respectively. The results suggested that highly porous cornstarch/n-HAp scaffold properties with adequate mechanical properties can be obtained for applications in bone tissue engineering.
      2  28