Displaying publications 1 - 20 of 66 in total

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  1. Fulltext Analysis of glass-reinforced epoxy material for radio frequency resonator
    Zaman MR, Islam MT, Misran N, Yatim B
    ScientificWorldJournal, 2014;2014:831435.
    PMID: 24977230 DOI: 10.1155/2014/831435
    A radio frequency (RF) resonator using glass-reinforced epoxy material for C and X band is proposed in this paper. Microstrip line technology for RF over glass-reinforced epoxy material is analyzed. Coupling mechanism over RF material and parasitic coupling performance is explained utilizing even and odd mode impedance with relevant equivalent circuit. Babinet's principle is deployed to explicate the circular slot ground plane of the proposed resonator. The resonator is designed over four materials from different backgrounds which are glass-reinforced epoxy, polyester, gallium arsenide (GaAs), and rogers RO 4350B. Parametric studies and optimization algorithm are applied over the geometry of the microstrip resonator to achieve dual band response for C and X band. Resonator behaviors for different materials are concluded and compared for the same structure. The final design is fabricated over glass-reinforced epoxy material. The fabricated resonator shows a maximum directivity of 5.65 dBi and 6.62 dBi at 5.84 GHz and 8.16 GHz, respectively. The lowest resonance response is less than -20 dB for C band and -34 dB for X band. The resonator is prototyped using LPKF (S63) drilling machine to study the material behavior.
    Matched MeSH terms: Computer-Aided Design
  2. Reflection spectra of etched FBGs under the influence of axial contraction and stress-induced index change
    Yang HZ, Lim KS, Qiao XG, Chong WY, Cheong YK, Lim WH, et al.
    Opt Express, 2013 Jun 17;21(12):14808-15.
    PMID: 23787668 DOI: 10.1364/OE.21.014808
    We present a new theoretical model for the broadband reflection spectra of etched FBGs which includes the effects of axial contraction and stress-induced index change. The reflection spectra of the etched FBGs with several different taper profiles are simulated based on the proposed model. In our observation, decaying exponential profile produces a broadband reflection spectrum with good uniformity over the range of 1540-1560 nm. An etched FBG with similar taper profile is fabricated and the experimental result shows good agreement with the theoretical model.
    Matched MeSH terms: Computer-Aided Design*
  3. Fulltext An alternate method to springback compensation for sheet metal forming
    Siswanto WA, Anggono AD, Omar B, Jusoff K
    ScientificWorldJournal, 2014;2014:301271.
    PMID: 25165738 DOI: 10.1155/2014/301271
    The aim of this work is to improve the accuracy of cold stamping product by accommodating springback. This is a numerical approach to improve the accuracy of springback analysis and die compensation process combining the displacement adjustment (DA) method and the spring forward (SF) algorithm. This alternate hybrid method (HM) is conducted by firstly employing DA method followed by the SF method instead of either DA or SF method individually. The springback shape and the target part are used to optimize the die surfaces compensating springback. The hybrid method (HM) algorithm has been coded in Fortran and tested in two- and three-dimensional models. By implementing the HM, the springback error can be decreased and the dimensional deviation falls in the predefined tolerance range.
    Matched MeSH terms: Computer-Aided Design*
  4. Low energy, low latency and high speed array divider circuit using a shannon theorem based adder cell
    Senthilpari C, Diwakar K, Singh AK
    Recent Pat Nanotechnol, 2009;3(1):61-72.
    PMID: 19149756
    The paper discuss the design of 1-bit full adder circuit using Shannon theorem. This proposed full adder circuit is used as one of the circuit component for implementation of Non- Restoring and Restoring divider circuits. The proposed adder and divider schematics are designed by using DSCH2 CAD tool and their layouts are generated by Microwind 3 VLSI CAD tool. The divider circuits are designed by using standard CMOS 0.35 microm feature size and corresponding power supply 3.5 V. The parameters analyses are carried out by BSIM 4 analysis. We have compared the simulated results of the Shannon based divider circuit with CPL and CMOS adder cell based divider circuits. We have further compared the results with published results and observed that the proposed adder cell based divider circuit dissipates lower power, gives faster response, lower latency, low EPI and high throughput.
    Matched MeSH terms: Computer-Aided Design*
  5. Effects of different implant-abutment connections on micromotion and stress distribution: prediction of microgap formation
    Saidin S, Abdul Kadir MR, Sulaiman E, Abu Kasim NH
    J Dent, 2012 Jun;40(6):467-74.
    PMID: 22366313 DOI: 10.1016/j.jdent.2012.02.009
    The aim of this study was to analyse micromotion and stress distribution at the connections of implants and four types of abutments: internal hexagonal, internal octagonal, internal conical and trilobe.
    Matched MeSH terms: Computer-Aided Design
  6. Computational evaluation of unsaturated carbonitriles as neutral receptor model for beryllium(II) recognition
    Rosli AN, Ahmad MR, Alias Y, Zain SM, Lee VS, Woi PM
    J Mol Model, 2014 Dec;20(12):2533.
    PMID: 25433601 DOI: 10.1007/s00894-014-2533-9
    Design of neutral receptor molecules (ionophores) for beryllium(II) using unsaturated carbonitrile models has been carried out via density functional theory, G3, and G4 calculations. The first part of this work focuses on gas phase binding energies between beryllium(II) and 2-cyano butadiene (2-CN BD), 3-cyano propene (3-CN P), and simpler models with two separate fragments; acrylonitrile and ethylene. Interactions between beryllium(II) and cyano nitrogen and terminal olefin in the models have been examined in terms of geometrical changes, distribution of charge over the entire π-system, and rehybridization of vinyl carbon orbitals. NMR shieldings and vibrational frequencies probed charge centers and strength of interactions. The six-membered cyclic complexes have planar structures with the rehybridized carbon slightly out of plane (16° in 2-CN BD). G3 results show that in 2-CN BD complex participation of vinyl carbon further stabilizes the cyclic adduct by 16.3 kcal mol(-1), whereas, in simpler models, interaction between beryllium(II) and acetonitrile is favorable by 46.4 kcal mol(-1) compared with that of ethylene. The terminal vinyl carbon in 2-CN BD rehybridizes to sp (3) with an increase of 7 % of s character to allow interaction with beryllium(II). G4 calculations show that the Be(II) and 2-CN BD complex is more strongly bound than those with Mg(II) and Ca(II) by 98.5 and 139.2 kcal mol(-1) (-1), respectively. QST2 method shows that the cyclic and acyclic forms of Be(II)-2-CN BD complexes are separated by 12.3 kcal mol(-1) barrier height. Overlap population analysis reveals that Ca(II) can be discriminated based on its tendency to form ionic interaction with the receptor models.
    Matched MeSH terms: Computer-Aided Design
  7. Fulltext G3 assisted rational design of chemical sensor array using carbonitrile neutral receptors
    Rosli AN, Bakar MA, Manan NS, Woi PM, Lee VS, Zain SM, et al.
    Sensors (Basel), 2013;13(10):13835-60.
    PMID: 24129020 DOI: 10.3390/s131013835
    Combined computational and experimental strategies for the systematic design of chemical sensor arrays using carbonitrile neutral receptors are presented. Binding energies of acetonitrile, n-pentylcarbonitrile and malononitrile with Ca(II), Mg(II), Be(II) and H⁺ have been investigated with the B3LYP, G3, CBS-QB3, G4 and MQZVP methods, showing a general trend H⁺ > Be(II) > Mg(II) > Ca(II). Hydrogen bonding, donor-acceptor and cation-lone pair electron simple models were employed in evaluating the performance of computational methods. Mg(II) is bound to acetonitrile in water by 12.5 kcal/mol, and in the gas phase the receptor is more strongly bound by 33.3 kcal/mol to Mg(II) compared to Ca(II). Interaction of bound cations with carbonitrile reduces the energies of the MOs involved in the proposed σ-p conjugated network. The planar malononitrile-Be(II) complex possibly involves a π-network with a cationic methylene carbon. Fabricated potentiometric chemical sensors show distinct signal patterns that can be exploited in sensor array applications.
    Matched MeSH terms: Computer-Aided Design
  8. Start-up, performance and optimization of a compost biofilter treating gas-phase mixture of benzene and toluene
    Rene ER, Kar S, Krishnan J, Pakshirajan K, López ME, Murthy DV, et al.
    Bioresour Technol, 2015 Aug;190:529-35.
    PMID: 25827361 DOI: 10.1016/j.biortech.2015.03.049
    The performance of a compost biofilter inoculated with mixed microbial consortium was optimized for treating a gas-phase mixture of benzene and toluene. The biofilter was acclimated to these VOCs for a period of ∼18d. The effects of concentration and flow rate on the removal efficiency (RE) and elimination capacity (EC) were investigated by varying the inlet concentration of benzene (0.12-0.95g/m(3)), toluene (0.14-1.48g/m(3)) and gas-flow rate (0.024-0.072m(3)/h). At comparable loading rates, benzene removal in the mixture was reduced in the range of 6.6-41% in comparison with the individual benzene degradation. Toluene removal in mixture was even more affected as observed from the reductions in REs, ranging from 18.4% to 76%. The results were statistically interpreted by performing an analysis of variance (ANOVA) to elucidate the main and interaction effects.
    Matched MeSH terms: Computer-Aided Design
  9. Design of new generation femoral prostheses using functionally graded materials: a finite element analysis
    Oshkour AA, Abu Osman NA, Yau YH, Tarlochan F, Abas WA
    Proc Inst Mech Eng H, 2013 Jan;227(1):3-17.
    PMID: 23516951
    This study aimed to develop a three-dimensional finite element model of a functionally graded femoral prosthesis. The model consisted of a femoral prosthesis created from functionally graded materials (FGMs), cement, and femur. The hip prosthesis was composed of FGMs made of titanium alloy, chrome-cobalt, and hydroxyapatite at volume fraction gradient exponents of 0, 1, and 5, respectively. The stress was measured on the femoral prosthesis, cement, and femur. Stress on the neck of the femoral prosthesis was not sensitive to the properties of the constituent material. However, stress on the stem and cement decreased proportionally as the volume fraction gradient exponent of the FGM increased. Meanwhile, stress became uniform on the cement mantle layer. In addition, stress on the femur in the proximal part increased and a high surface area of the femoral part was involved in absorbing the stress. As such, the stress-shielding area decreased. The results obtained in this study are significant in the design and longevity of new prosthetic devices because FGMs offer the potential to achieve stress distribution that more closely resembles that of the natural bone in the femur.
    Matched MeSH terms: Computer-Aided Design
  10. Effect of CAD-CAM porcelain veneers thickness on their cemented color
    Omar H, Atta O, El-Mowafy O, Khan SA
    J Dent, 2010;38 Suppl 2:e95-9.
    PMID: 20493232 DOI: 10.1016/j.jdent.2010.05.006
    To determine the effect of thickness of porcelain veneers constructed from CAD-CAM on their final color when two resin cements were used.
    Matched MeSH terms: Computer-Aided Design*
  11. Fulltext Detail reproduction of elastomeric materials: effect of viscosity and groove geometry
    Nik Zarina Nik Mahmood, Noor Hayaty Abu Kasim, Mamat Azuddin, Noor Lide Abu Kassim
    Compendium of Oral Science, 2015;2(1):21-31.
    MyJurnal
    Objective: To evaluate the effect of type of viscosity and groove on surface detail reproduction of elastomeric impression materials. Methods: Two polyvinylsiloxane and polyether elastomeric impression materials were investigated. An aluminium cylindrical reference block with V- and U-shaped grooves of 1 mm and 2 mm in depth was machined using CAD-CAM system. Impressions of the block were taken to produce 35 master dies. Each die was immersed in distilled water for 5 minutes prior to impression making. Surface topography of the dies and impressions were captured using Alicona Imaging System. Mean difference in depth between the mas-ter dies and corresponding impressions’ grooves were analyzed. Results: Type of viscosities and groove showed significant main effects on surface detail (p < .01), but no significant interaction was observed between the two (p > .01). Express™ putty/light exhibited the lowest mean difference in depth for all grooves. The highest mean difference for U1 (38.3μm ± 21.55), U2 (52.96μm ± 30.39),V1 (45.02μm ± 34.82) and V2 (58.44μm ± 44.19) was obtained from Impregum medium, Aquasil medium, Impregum™ heavy/light and Impregum™ heavy/light groups respectively. Conclusion: Express putty/light-bodied material produced the best surface detail, and U-shaped groove showed superior detail reproduction.
    Matched MeSH terms: Computer-Aided Design
  12. Wind tunnel and numerical data on the ventilation performance of windcatcher with wing wall
    Nejat P, Calautit JK, Abd Majid MZ, Hughes BR, Zeynali I, Jomehzadeh F
    Data Brief, 2016 Dec;9:448-452.
    PMID: 27709121
    The data presented in this article were the basis for the study reported in the research articles entitled "Evaluation of a two-sided windcatcher integrated with wing wall (as a new design) and comparison with a conventional windcatcher" (P. Nejat, J.K. Calautit, M.Z.A. Majid, B.R. Hughes, I. Zeynali, F. Jomehzadeh, 2016) [1] which presents the effect of wing wall on the air flow distribution under using the windcatchers as a natural ventilation equipment. Here, we detail the wind tunnel testing and numerical set-up used for obtaining the data on ventilation rates and indoor airflow distribution inside a test room with a two-sided windcatcher and wing wall. Three models were integrated with wing wall angled at 30°, 45° and 60° and another windcatcher was a conventional two-sided device. The computer-aided design (CAD) three-dimensional geometries which were produced using Solid Edge modeler are also included in the data article.
    Matched MeSH terms: Computer-Aided Design
  13. Fulltext Development of simple designs of multitip probe diagnostic systems for RF plasma characterization
    Naz MY, Shukrullah S, Ghaffar A, Rehman NU
    ScientificWorldJournal, 2014;2014:279868.
    PMID: 24683326 DOI: 10.1155/2014/279868
    Multitip probes are very useful diagnostics for analyzing and controlling the physical phenomena occurring in low temperature discharge plasmas. However, DC biased probes often fail to perform well in processing plasmas. The objective of the work was to deduce simple designs of DC biased multitip probes for parametric study of radio frequency plasmas. For this purpose, symmetric double probe, asymmetric double probe, and symmetric triple probe diagnostic systems and their driving circuits were designed and tested in an inductively coupled plasma (ICP) generated by a 13.56 MHz radio frequency (RF) source. Using I-V characteristics of these probes, electron temperature, electron number density, and ion saturation current was measured as a function of input power and filling gas pressure. An increasing trend was noticed in electron temperature and electron number density for increasing input RF power whilst a decreasing trend was evident in these parameters when measured against filling gas pressure. In addition, the electron energy probability function (EEPF) was also studied by using an asymmetric double probe. These studies confirmed the non-Maxwellian nature of the EEPF and the presence of two groups of the energetic electrons at low filling gas pressures.
    Matched MeSH terms: Computer-Aided Design*
  14. Fulltext The effectiveness of interactive learning in manufacturing engineering
    Nadia Abdul Rani, Faieza Abdul Aziz, Rohidatun M,W.
    Journal of Engineering and Science Research, 2018;2(6):10-16.
    MyJurnal
    Interactive learning is a pedagogical model that encourages students to be part of the lesson instead of passive observers, quietly sitting at a desk taking notes or memorizing information. Students interact with the material, each other and the teacher in an active way. The new emerging technologies that can overcome some of the potential difficulties in this area includes computer graphics, augmented reality, computational dynamics, and virtual worlds. Therefore, the manufacturing industry relies on new design concepts and methods undertake the challenges in integrating technologies to expedite the march towards industrial revolution 4.0.This paper reviews and investigates the current context of the use of interactive learning such as Virtual Reality(VR),Augmented Reality(AR),Computer aided design and manufacturing(CADCAM), computer graphics, computational dynamics and new emerging technologies that effect on students and lectures in learning and teaching environments for Manufacturing Engineering. Interactive learning is part of the factors that could influence the self-learning and regulations environments.
    Matched MeSH terms: Computer-Aided Design
  15. Fulltext Analysis and optimization of spiral circular inductive coupling link for bio-implanted applications on air and within human tissue
    Mutashar S, Hannan MA, Samad SA, Hussain A
    Sensors (Basel), 2014;14(7):11522-41.
    PMID: 24984057 DOI: 10.3390/s140711522
    The use of wireless communication using inductive links to transfer data and power to implantable microsystems to stimulate and monitor nerves and muscles is increasing. This paper deals with the development of the theoretical analysis and optimization of an inductive link based on coupling and on spiral circular coil geometry. The coil dimensions offer 22 mm of mutual distance in air. However, at 6 mm of distance, the coils offer a power transmission efficiency of 80% in the optimum case and 73% in the worst case via low input impedance, whereas, transmission efficiency is 45% and 32%, respectively, via high input impedance. The simulations were performed in air and with two types of simulated human biological tissues such as dry and wet-skin using a depth of 6 mm. The performance results expound that the combined magnitude of the electric field components surrounding the external coil is approximately 98% of that in air, and for an internal coil, it is approximately 50%, respectively. It can be seen that the gain surrounding coils is almost constant and confirms the omnidirectional pattern associated with such loop antennas which reduces the effect of non-alignment between the two coils. The results also show that the specific absorption rate (SAR) and power loss within the tissue are lower than that of the standard level. Thus, the tissue will not be damaged anymore.
    Matched MeSH terms: Computer-Aided Design*
  16. Fulltext Degradation effects of dietary solvents on microhardness and inorganic elements of computer-aided design/computer-aided manufacturing dental composites
    Munusamy SM, Helen-Ng LC, Farook MS
    BMC Oral Health, 2024 Feb 01;24(1):162.
    PMID: 38302972 DOI: 10.1186/s12903-024-03905-7
    BACKGROUND: Computer-aided design/computer-aided manufacturing (CAD/CAM) dental composites were introduced with superior mechanical properties than conventional dental composites. However, little is known on effects of dietary solvents on microhardness or inorganic elemental composition of CAD/CAM composites.

    OBJECTIVES: The objectives of this study were to evaluate the degradation effects of each dietary solvent on the microhardness of the different CAD/CAM dental composites and to observe the degradation effects of dietary solvent on the inorganic elements of the dental composites investigated.

    METHODS: Fifty specimens with dimensions 12 mm x 14 mm x 1.5 mm were prepared for direct composite (Filtek Z350 XT [FZ]), indirect composite (Shofu Ceramage [CM]), and three CAD/CAM composites (Lava Ultimate [LU], Cerasmart [CS], and Vita Enamic [VE]). The specimens were randomly divided into 5 groups (n = 10) and conditioned for 1-week at 37°C in the following: air (control), distilled water, 0.02 N citric acid, 0.02 N lactic acid and 50% ethanol-water solution. Subsequently, the specimens were subjected to microhardness test (KHN) using Knoop hardness indenter. Air (control) and representative postconditioning specimens with the lowest mean KHN value for each material were analyzed using energy dispersive X-ray spectroscopy (EDX). Statistical analysis was done using one-way ANOVA and post hoc Bonferroni test at a significance level of p = 0.05.

    RESULTS: Mean KHN values ranged from 39.7 ± 2.7 kg/mm2 for FZ conditioned in 50% ethanol-water solution to 79.2 ± 3.4 kg/mm2 for VE conditioned in air (control). With exception to LU, significant differences were observed between materials and dietary solvents for other dental composites investigated. EDX showed stable peaks of the inorganic elements between air (control) and representative postconditioning specimens.

    CONCLUSIONS: The microhardness of dental composites was significantly affected by dietary solvents, except for one CAD/CAM composite [LU]. However, no changes were observed in the inorganic elemental composition of dental composites between air (control) and 1-week postconditioning.

    Matched MeSH terms: Computer-Aided Design
  17. Fulltext internal fit of CAD/CAM fabricated metal alloy fixed partial dentures
    Mohd Faiz Nasruddin, Theocharospoulos, Antonios, Ray, Noel, Burke, Francis M.
    Compendium of Oral Science, 2016;3(1):1-8.
    MyJurnal
    Fitting accuracy of dental prostheses is essential for clinical success. An ideal marginal and internal fit will minimize plaque accumulation, gingival irritation, cement dissolution and micro leakage as well as enhancing the mechanical behaviour of a fixed partial denture (FPD) (1). Unfortunately, there is disagreement about acceptable marginal and internal fit discrepancies of FPD’s (2) from 75-200μm. There are two main manufacturing routes of CAD/CAM FPD’s: the subtractive and the additive route. The subtractive route is a top-down approach which involves milling the desired article out of a block of the material of choice using a series of burs. This route is currently the most common CAD/CAM technique for the fabrication of metal alloy FPD’s. The additive route is a bottom-up approach where the desired article is fabricated layer by layer out of the material of choice. Examples include selective laser sintering and selective laser melting for metal alloy FPD’s.
    Matched MeSH terms: Computer-Aided Design
  18. Fulltext Single-event-upset sensitivity analysis on low-swing drivers
    Mahyuddin NM, Russell G
    ScientificWorldJournal, 2014;2014:876435.
    PMID: 24782671 DOI: 10.1155/2014/876435
    Technology scaling relies on reduced nodal capacitances and lower voltages in order to improve performance and power consumption, resulting in significant increase in layout density, thus making these submicron technologies more susceptible to soft errors. Previous analysis indicates a significant improvement in SEU tolerance of the driver when the bias current is injected into the circuit but results in increase of power dissipation. Subsequently, other alternatives are considered. The impact of transistor sizes and temperature on SEU tolerance is tested. Results indicate no significant changes in Q(crit) when the effective transistor length is increased by 10%, but there is an improvement when high temperature and high bias currents are applied. However, this is due to other process parameters that are temperature dependent, which contribute to the sharp increase in Q(crit). It is found that, with temperature, there is no clear factor that can justify the direct impact of temperature on the SEU tolerance. Thus, in order to improve the SEU tolerance, high bias currents are still considered to be the most effective method in improving the SEU sensitivity. However, good trade-off is required for the low-swing driver in order to meet the reliability target with minimal power overhead.
    Matched MeSH terms: Computer-Aided Design
  19. Simplified ASE correction algorithm for variable gain-flattened erbium-doped fiber amplifier
    Mahdi MA, Sheih SJ, Adikan FR
    Opt Express, 2009 Jun 08;17(12):10069-75.
    PMID: 19506658
    We demonstrate a simplified algorithm to manifest the contribution of amplified spontaneous emission in variable gain-flattened Erbium-doped fiber amplifier (EDFA). The detected signal power at the input and output ports of EDFA comprises of both signal and noise. The generated amplified spontaneous emission from EDFA cannot be differentiated by photodetector which leads to underestimation of the targeted gain value. This gain penalty must be taken into consideration in order to obtain the accurate gain level. By taking the average gain penalty within the dynamic gain range, the targeted output power is set higher than the desired level. Thus, the errors are significantly reduced to less than 0.15 dB from 15 dB to 30 dB desired gain values.
    Matched MeSH terms: Computer-Aided Design
  20. Stress distributions in maxillary central incisors restored with various types of post materials and designs
    Madfa AA, Kadir MR, Kashani J, Saidin S, Sulaiman E, Marhazlinda J, et al.
    Med Eng Phys, 2014 Jul;36(7):962-7.
    PMID: 24834856 DOI: 10.1016/j.medengphy.2014.03.018
    Different dental post designs and materials affect the stability of restoration of a tooth. This study aimed to analyse and compare the stability of two shapes of dental posts (parallel-sided and tapered) made of five different materials (titanium, zirconia, carbon fibre and glass fibre) by investigating their stress transfer through the finite element (FE) method. Ten three-dimensional (3D) FE models of a maxillary central incisor restored with two different designs and five different materials were constructed. An oblique loading of 100 N was applied to each 3D model. Analyses along the centre of the post, the crown-cement/core and the post-cement/dentine interfaces were computed, and the means were calculated. One-way ANOVAs followed by post hoc tests were used to evaluate the effectiveness of the post materials and designs (p=0.05). For post designs, the tapered posts introduced significantly higher stress compared with the parallel-sided post (p<0.05), especially along the centre of the post. Of the materials, the highest level of stress was found for stainless steel, followed by zirconia, titanium, glass fibre and carbon fibre posts (p<0.05). The carbon and glass fibre posts reduced the stress distribution at the middle and apical part of the posts compared with the stainless steel, zirconia and titanium posts. The opposite results were observed at the crown-cement/core interface.
    Matched MeSH terms: Computer-Aided Design
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