Top-Oil Temperature (TOT) is one of the basic components to estimate the Hot-Spot temperature (HST) of the transformers. This paper presents an alternative TOT model based on the heat transfer theory that utilises Nonlinear Thermal Resistance (NTR) and Lumped Capacitance (LC) approaches. It is applied in a thermal-electrical analogy and the heat transfer equivalent equation is determined. This model is tested on a measured TOT of 250 MVA ONAF and 400 MVA ONAF transformers obtained from IEC 60076-7 and previous research. A comparison of TOT is carried out with the existing models IEC 60076-7 exponential and IEEE Loading Guide clause 7 methods. It is found that the thermal model based on the NTR and LC approach could determine the measured TOT closer than the existing methods available in the standards.
In dentistry, determining position and orientation parameters for each tooth mostly based on orthodontic
qualitative perception. There is no quantitative method to obtain those parameters in three dimensional
(3D) images, especially in some complicated cases. This study proposed a quantitative approach for
locating centroid of tooth position and also its frame axes orientation. Based on Cone Beam Computed
Tomography (CBCT) x-ray images, a 3D model of teeth was obtained to visualise dental features. A
few dental features were used to calibrate the location of centroid and identify tooth reference axes, or
frames. Two definitions of centroid and frame axes were proposed for single root and for multiple roots
of teeth. Based on these two definitions, the positions and orientations of each tooth were determined
and evaluated. Teeth positions and orientations were obtai
Titanium (Ti) and Ti-based alloys presence the most widely applied as advanced biomaterials
in biomedical implant applications. Moreover, these alloys are known to be the most
valuable metallic materials including spinal cord surgical treatment. It becomes an interest
due to its advantages compared to others, including its bio compatibility and corrosion
resistant. However, an issue arises when it comes for permanent implant application as
the alloy has a possible toxic effect produced from chemical reaction between body fluid
environments with alloys chemical compositions. It also relies on the performance of
neighbouring bone tissue to integrate with the implant surface. Abnormalities usually
happen when surrounding tissue shows poor responses and rejection of implants that would
leads to body inflammation. These cause an increase in foreign body reaction leading to
severe body tissue response and thus, loosening of the implant. Corrosion effects and
biocompatibility behaviour of implantation usage also become one of the reasons of
implant damage. Here, this paper reviews the importance of using Ti and Ti-based alloys
in biomedical implantation, especially in orthopaedic spinal cord injury. It also reviews the
basic aspects of corrosion effects that lead to implant mechanical damage, poor response
of body rejection and biocompatibility behaviour of implantation usage.
The global Tuberculosis epidemic (TB) poses a significant public health threat. While the consequences of TB treatment interruption are indisputable, the knowledge about the timing and prognostic factors of TB treatment interruption is fundamental. Despite a considerable amount of evaluation, the timing and prognostic factors of TB treatment interruption have been inconsistently identified from one study to another. Therefore, this study aimed to examine the evidence obtained from published literature on the timing and prognostic factors of TB treatment interruption at different points of the treatment course. In this review, three databases namely Pubmed, Scopus, and Science Direct were used to identify articles published from January 2003 to February 2018. This was based on the inclusion criteria and keywords including ‘default’, ‘survival time’, ‘tuberculosis’, and ‘treatment interruption’. The nine selected studies were prospective and retrospective cohort studies conducted in developing countries. The diversity of the study’s participants and TB treatment interruption definition were allowed, thus delineating a heterogeneous finding. This review suggests that the interruption predominantly occurred during the maintenance phase of treatment course. Despite the finding, a considerable gap in understanding the prognostic factors at different time points of TB treatment interruption was elicited. The heterogeneity across the studies may limit the inferences and warrant further evaluation. In essence, the time-related information should be integrated into framing impactful public health strategy, while a vigorous attempt on the evaluation of the cognitive, behavioural and psychosocial aspects may be beneficial.
The tone of peking 1, 2, 3, 5, 6, 1’ was investigated using time-frequency analysis (TFA). The frequencies were measured using PicoScope oscilloscope, Melda analyzer in Cubase version 9 and Adobe version 3. Three different approaches for time-frequency analysis were used: Fourier spectra (using PicoScope), spectromorphology (using Melda analyzer) and spectrograms (using Adobe). Fourier spectra only identify intensity-frequency within entire signals, while spectromorphology identify the changes of intensity-frequency spectrum at fixed time and Adobe spectrograms identify the frequency with time. PicoScope reading produces the spectra of the fundamental and overtone frequencies in the entire sound. These overtones are non-harmonic since they are non-integral multiples of the fundamental. The fundamental frequencies of peking 1, 2, 3, 5, 6 were 1066Hz (C6), 1178Hz (D6), 1342Hz (E6), 1599Hz (G6) and 1793Hz (A6) respectively while peking 1’was 2123Hz (C7) i.e. one octave higher than peking 1. Melda analyzer reading proved that all peking sustained the initial fundamental frequency and overtone at t=0 until 2s. TFA from Adobe reading provides a description of the sound in the time-frequency plane. From TFA, peking 1, 2 and 6 exhibited a much gentler attack and more rapid decay than peking 3, 5 and 1’.
Gamelan in general is categorized as a group of gongs. This traditional Malay gamelan ensemble is in a slendro scale i.e. five notes per octave. The rhythms, pitch, duration and loudness classify the various groups of gongs such as bonang, kenong, gender, peking and gambang. The cast bronze peking, kenong and bonang were chosen from a range of Malay gamelan ensemble from Universiti Malaysia Sarawak (UNIMAS), Universiti Putra Malaysia (UPM), Universiti Kebangsaan Malaysia (UKM) and Universiti Teknologi Mara (UiTM). The sounds were recorded by PicoScope Oscilloscope. The PicoScope software displays waveform and spectrum in time and frequency domain respectively. The peking lowest and highest frequencies from UiTM were 293 Hz and 1867 Hz, from UPM were 644 Hz and 1369 Hz, from UKM were 1064 Hz and 2131 Hz and from UNIMAS were 1072 Hz and 2105 Hz respectively. The kenong lowest and highest frequencies from UiTM were 259 Hz and 463 Hz, from UPM were 294 Hz and 543 Hz, from UKM were 300 Hz and 540 Hz and from UNIMAS were 293 Hz and 519 Hz respectively. The fundamental frequencies of bonang from UPM were higher than that of UKM, UiTM and UNIMAS. The harmonics were not successive but interrupted by another frequency. The harmonics of each bonang was similar except for gamelan from UKM.
This paper presents two gear driven wind turbine generators (WTG) feeding a single three level grid connected NPC inverter. Each component of WTG is made up of wind turbine, 2-mass gear drive, permanent magnet synchronous generator (PMSG), AC-DC-AC power converter. A simple advanced hill climbs search (AHCS) maximum power point tracking algorithm that uses the mechanical power from the Wind turbine was developed to generate proper duty cycle for the control of single stage DC/DC boost converter. The DC link voltages are series interconnected and fed to a sinusoidal pulse width modulation (SPWM) controlled high power inverter. The complete model is simulated using MATLAB/ SIMULINK software under fixed and fluctuating wind speed conditions. Simulation results have shown that WECs exhibit variability in their output power as a result of changes in their prime movers (wind speed).
In this study, papaya (Carica papaya) peel was dried using convection oven and microwave drying methods to investigate the drying kinetics and the drying behavior in the attempt to search for a feasible way to utilize waste peel. Three different drying temperatures (45, 55, and 65 oC) and microwave powers (250, 440, and 600 W) were applied to dry the papaya peel, wherein the drying data were fitted into the following seven drying kinetic models: Lewis, Page, Modified Page, Henderson and Pabis, Logarithmic, Two-Term, and Approximation of Diffusion models. The study outcomes indicated that the Page model emerged as the best fitted model for oven drying of papaya peels with the highest coefficient of determination (R2) value (0.994-0.996) for all the three temperatures. As for microwave drying, the Approximation of Diffusion model exhibited the best fit owing to the highest R2 value (0.996-0.999) for all the three powers. The effective moisture diffusivity values for convection oven and microwave drying methods ranged from 6.65 x 10-08 to 4.35 x 10-07 and from 2.43 x 10-07 to 6.67 x 10-07, respectively. Additionally, the activation energy values were recorded at 61.301 kJ/mol and 46.621 W/g for oven and microwave drying methods, respectively.
This paper studied the thermal behaviour of pineapple leaf fibre (PALF) reinforced high impact polystyrene (HIPS) composite. Thermogravimetric analysis (TGA) and differential scanning calorimetric (DSC) analysis were used to measure the thermal characteristic of HIPS/PALF composites. In particular, the TGA analysis was utilized to measure the degradation and decomposition of materials in neat polystyrene, pineapple fibre, and the composites. The measurements were carried out in the temperature of 25°C – 800°C, at a heating rate of 20°C min-1 and the nitrogen gas flow was 50 mL min-1. The temperature of the DSC analysis was programmed to be between 25°C – 300°C. The results from TGA analysis show that the addition of pineapple fibre has improved the thermal stability of the composites as compared to neat HIPS. In addition, the effects of compatibilising agent and surface modification of PALF with alkali treated were also determined and compared.
Thermal characterization of sugar palm fibre (SPF), reinforced high impact polystyrene (HIPS)
composites, was studied by means of thermogravimetric analysis. The effects of alkaline treatment and compatibilizing agent on the thermal stability of the composites were evaluated. Alkaline treatment was carried out by soaking the fibres in 4 and 6% of NaOH solution, while treatment with compatibilizing agent was employed by adding 2 and 3% maleic anhydride-graft-polystyrene (MA-g-PS) to the composites. Both the treatments were aimed to improve the mechanical performance of the composites. From the study, the thermal stability of the treated composites was found to be higher than that of untreated composites. It is shown that the incorporation of sugar palm fibre influences the degree of thermal stability of the composites. The treatments on composites also contributed to shifting the peak temperature of degradation of the composites. In other words, there are strong chemical reactions between the components of the treated composites. The thermal stability of the composites, with alkaline treatment and compatibilizing agent, was found to be better as compared to those of the untreated composites.
In the moving layer of particles with variable concentration, the shear estimation is not directly predictable and there is no existing clear mathematical or empirical formula to achieve this objective. This paper presents a developed approach to estimate the shear forces in a flow having suspended and moving layers of solid particles in liquid flow. The two-layer approach was taken whereby the flow consisting of one upper suspended layer of particles in the liquid, and the bottom layer was the moving bed of particles. In the present work, the method of finding the force acting on the pipe wall by the particles in the layer, termed as the ‘dry force’, was presented using a “pseudo hydrostatic pressure” method. To attain the equation for the dry force, a mathematical approach is taken with the assumptions that the flow is horizontal, two-phase pipe flow (solid in Newtonian liquid), incompressible and it is at steady-state. The analysis was conducted considering various particles densities, various concentrations in the suspended layer and different thicknesses of the moving bed. Changing the concentration in the suspended layer from 0.00001 up to 0.001 didn’t showed significant changes in the dry force evaluation. The dry friction force is increasing with increasing moving bed thickness. The developed mathematical model can be
applicable in solving for the shear force in horizontal solid liquid two-phase flows.
The improvement of the composite material against fatigue loading is of a great interest. In this study, the classical lamination theory of laminated composite was developed in order to include the effect of fibre prestressing on the composite’s fatigue life when it was subjected to tension-tension fatigue loading. The biaxial fabric prestress term of the plain-weave composite (E-glass/polyester) was included in the theory and simplified. The overall tensile stress within the composite lamina was reduced by inducing compressive residual stress imparted from releasing the fibre pretension load. The fatigue life of the prestressed E-glass/polyester composite lamina was prolonged 36 times compared to the non-prestressed counterparts when the fabric was biaxially prestressed with 100 MPa.
This study sought to prospectively evaluate the influence of contrasted fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDGPET/CT) in the staging of and impact on the management plan for treatment in patients with nasopharyngeal carcinoma (NPC). A total of 14 histologically proven NPC patients (mean age: 44.64±4.01years) were included in the study. These patients underwent contrasted Computed Tomography (CT) as well as 18F-FDGPET/CT imaging. Staging was based on the 7th edition of the American Joint Committee on Cancer Tumor Node Metastases (AJCCTNM) recommendations.The oncologist was asked to prospectively assign a treatment plan for all patients being evaluated by CT and 18F-FDGPET/CT. The treatment plans were compared with the incremental information supplied by the FDG-PET/CT. The maximum standardised uptake value (SUVmax) and the widest dimension of the primary tumour, cervical lymph nodes size and the distant metastatic lesions were quantified on the co-registered PET/CT images by two experienced nuclear radiologists. The contrasted 18F-FDGPET/CT changed the management intent in nine patients (64.7%). A univariate analysis showed that there were significant correlations between SUVmax and the size of the metastatic
lymph nodes (R2 =0.0761, p
The aim of this study was to evaluate the value of MRI spectroscopy and association with the altered glucose metabolism on 18-FDG PET/CT in patients with suspicious breast cancer. Eight selected breast cancer patients with BIRADS 4 or 5 on mammogram were recruited and patients underwent 18F-FDG PET/CT MRI (spectroscopy). The standardise uptake value (SUVmax) was analysed to determine the degree of the altered glucose metabolism on the PET. The metabolites of tumor lesions were measured using in vivo proton MR spectroscopy (MRS) of the breast. There were eight females with a mean age of 55.3±12.2 years with a biopsy result of invasive ductal carcinoma (2), lobular carcinoma (1) and benign lesion (5). There was a significant difference between the mean of the malignant tumour (SUVmax 4.28±3.74 g/ml) and the mean of the benign tumour (SUVmax: 2.33±0.9 g/ml). On the per-lesional basis of the MRS correlate with SUVmax, the suspicious breast tissue exhibited raised creatinine metabolites (mean: 3.39±0.54u) with significant correlation SUVmax mean 3.06±2.34 as compared to N-acetyl Aspartate (NAA), (mean: 2.84±0.99u) and choline (mean: 2.46± 0.70 u). This study showed that high SUVmax was associated with malignant cancer and the high creatinine metabolite that correlated with the SUVmax could potentially be utilised as a surrogate marker in detecting breast cancer.
Phenol Formaldehyde (PF) resin has been extensively used in the manufacturing industry as a binding agent, especially in the production of wood-based panels because of its ability to provide good moisture resistance, exterior strength and durability as well as excellent temperature stability. However, due to the use of limited petroleum-based phenol in its formulation, there is a strong interest in exploring renewable biomass material to partially substitute the petroleum-based phenol. In this study, the slow pyrolysis of biomass decomposition process was used to convert two types of biomass, namely, oil palm frond and Rhizophora hardwood, into bio-oil. The phenol-rich fraction of the bio-oil was separated and added into the formulation of PF resin to produce an environmentally-friendly type of PF resin, known as bio-oilphenol-formaldehyde (BPF) resin. This BPF resin was observed to have comparable viscosity, better alkalinity, improved non-volatile content and faster curing temperature than conventional PF resin. Moreover, the particleboard bonded with this BPF resin was observed to have just as excellent bonding strength as the one bonded using conventional PF resin. However, the BPF resin exhibited an increased level of free formaldehyde and less thermal stability than the conventional PF resin, probably due to the addition of the less reactive bio-oil.
This paper presents a new approach to identify fatigue damaging potential locations using the Morlet wavelet coefficients. For solving the subject matter, the 122.4 second SAESUS strain signal was selected for the simulation purpose. As the result, the Morlet wavelet coefficients predicted that the maximum fatigue damage occurs at 40.4 - 42.6 seconds and 67.4 - 70 seconds. For the validation purpose, the Morrow’s fatigue damaging value was calculated and was obtained that the maximum fatigue damage occurs at 0 seconds and 99.7 seconds. The fatigue damaging value at the points was 0.0047 cycles to failure. Since both the plots had similar pattern, the Morlet wavelet coefficients could be used as the early warning of the fatigue damaging potential locations, although the locations were not entirely correct.
Similarity measurement is a critical component in any case-based reasoning (CBR) system. CBR is
a superior technique for solving new problems based on previous experiences. Main assumption in
CBR relies on the hypothesis that states similar problems should have similar solutions. This paper
describes a comparative analysis on several commonly used similarity measures (Canberra, Clark, and Normalized Euclidean distance) in retrieving phase of the case-based reasoning approach to facilitate supplier selection. In addition, the proposed agent-based supplier selection framework was designed to use customer’s defined weights to evaluate the price, volume, quality grade, and delivery date of supply materials, and also provide them with alternative products which are closest to their first order if it was out of stock. Finally, based on the proposed framework, a numerical example of the used approach is illustrated.
In this study, oil palm fruit bunch fiber (OPEFB) was used as a secondary filler in HDPE/clay nanocomposites. The composites were prepared by melt compounding, containing high density polyethylene (HDPE), OPEFB fibers, Maleic anhydride grafted polyethylene (MAPE) and four different clay loading (3, 5, 7 and 10 PE nanoclay masterbatch pellets per hundred HDPE pellets). Four OPEFB sizes (180 μm, 250 μm, 300 μm and 355 μm) were added in the composites to investigate its effects on the fracture toughness and impact strength. Fracture toughness of the composites was determined according to ASTM D5045 and single edge notch bending (SENB) was employed during the test while impact tests were performed according to ASTM D256. The effects of alkali treatment were also investigated in this study. The result indicates that the fracture toughness slightly increased as clay loading increased. The highest value of fracture toughness was 0.47 and 1.06 MPa.m1/2 at 5 phr for both types of composites. The presence of OPEFB fiber as a secondary filler in the matrix indicates significant enhancement of fracture toughness up to 133%. However, its impact strength seems to deteriorate with the presence of OPEFB fiber.
The increasing adoption of social media is a viable means in crowdsourcing. It can facilitate the connectivity of collaboration between different organisations, people and society to produce innovative and cost-effective solutions to many problems. Social media have opened up unprecedented new possibilities of engaging the public in meaningful ways through crowdsourcing. However, the growing number of security and privacy issues in social media may weaken the efficacy of crowdsourcing. This study aims to provide a basic understanding of security and privacy issues in line with the growth of crowdsourcing using social media platforms. This study also illustrates how crowdsourcing and social media data can lead to security and privacy issues in different environments. Lastly, this study proposes future works that may serve as direction for scholars to explore security and privacy in crowdsourcing through social media platforms. Secondary sources obtained from journals, conference papers, industry reports and books were reviewed to gather information.
The core losses in a three phase transformer can be significantly reduced by improving the core joint geometry. The researchers were applied numerous types of T-joint designs in order to reach the optimum design that can be used in three phase transformer to reduction the losses. Two types of T-joint design are presented in this paper; T-joint with 90° butt-lap design and T-joint with 45° mitered design. A 3-phase distribution transformer was simulated in 3D using Ansys Maxwell software. The core loss for a three-leg three phase transformer rated 1000 KVA and the flux density distribution are investigated. The simulation results show the core losses were increased up to 3% and the flux density was increased to reach more than 22% flux density become higher when using T-joint with 90° butt-lap design as compared with T-joint with 45° mitered design.