UniMAP RIS :: Browsing Publications 2017 by Issue Date

Publication

Synthesis of silicon carbide nanowhiskers by microwave heating: Effect of heating duration

( 2017-01-01)

Kahar S.

;

Voon C.

;

Lee C.

;

Gopinath S.

;

Arshad M.

;

Lim B.

;

Foo K.

;

Hashim U.

SiC nanowhiskers (SiCNWs), dueto their unique properties such as high thermal stability, high strength, high thermal conductivity and large band gap, lead to a wide range of applications. In this article, synthesis of SiCNWs was performedby using microwave heating. Silica and graphite in the ratio of 1:3 were mixed in an ultrasonic bath, dried on a hotplate and cold pressed uniaxially into a pellet die. The pellets were heatedbyusingalaboratory microwave furnaceto 1400 °C witha heating rate of 20 °C min-1and heated for 20,40and60 min. Characterizationsof the as synthesized SiCNWs were done tostudy the effect ofheating duration onthe morphology and properties of SiCNWs. A time of 40 min was foundto bethe most ideal heating duration for the synthesisof SiCNWs. β-SiC appeared as the only phaseinthe x-ray diffraction pattern for SiCNWs formed byusing40and 60 min of heating duration with no traces of unreacted silica and graphite. Field emission scanning electron microscopy imaging confirmed thatnotrace of graphiteor silica was present in SiCNWs synthesized by a heating duration of 40 and 60 min. Energy dispersive x-ray spectroscopy analysis revealed that only elemental C and Siwere present for SiCNWs synthesizedat 40and60 min. Meanwhile, photoluminescence spectroscopy indicated the presence of single phase β-SiC peakat 440 nmwas associated with band gap of 2.8 eV. Absorption bands of Si-C bond were detected at 802.4 cm-1 in the spectra of fourier transform infrared analysis. SiCNWs produced byheatingat40 and 60 min have high thermal stability with weight loss lower than 6%. A simple process that involved two steps of ultrasonic mixing and microwave heating of graphite and SiO2 is proposed as a new route for the synthesisof SiCNWs.

Publication

Impact of secondary phases content on the mechanical properties of cordierite

( 2017-01-01)

Eing Kuan Kok

;

Banjuraizah Johar

;

Ho Li Ngee

;

Zabar Yahidah

The Cordierite ceramic body had been synthesized through conventional techniques solid state reaction by using non-stoichiometric composition (2.5 MgO. 1.8 Al2O3. 5 SiO2). The sintering temperature study was carried out by heat treated the samples at several degree of sintering temperature (1250 °C, 1275 °C, 1300 °C, 1325 °C, 1350 °C and 1375 °C). The qualitative and quantitative of crystalline phase analysis was accomplished by using X-ray Diffraction (XRD) technique and Rietveld structural refinement. The Scanning electron microscopy (SEM) was employed for morphology analysis. The mechanical properties of samples were determined by Vicker's Hardness test. Rietveld quantitative phase analysis results show that α phase Cordierite constitutes up to 96.4 wt% when the samples was sintered for 2 hours at sintering temperature of 1375 °C and obtained densified and orderly crystal structure arrangement in SEM micrograph except the mechanical strength. The sample obtained the uppermost α phase Cordierite content gained the lowest hardness values (4.0±0.8GPa). Conversely, the sample contains 90 wt% α-cordierite and 1.4 wt% magnesium titatnate achieve highest hardness which is about 4.9±0.79GPa.

Publication

The effect of liquid natural rubber as toughening agent in epoxy/LNR/CB composite

( 2017-01-01)

Fauzi F.S.

;

Teh P.L.

;

Du N.U.L.

;

Yeoh C.K.

Liquid natural rubber (LNR) was used as the toughening agent to overcome the brittleness of epoxy thermoset matrix. The LNR were prepared by using depolymerization method. The experiment was consist of two parts of study, first, epoxy filled with carbon black to get the optimun 15 vol.% content of carbon black (CB). Second, epoxy with various amount LNR and at 15 vol.% CB content. This can be seen from the result of flexural properties testing, fracture toughness testing and SEM morphology. The best properties of LNR as toughening as 4 phr because it gave optimun performance compared to others LNR content.

Publication

Experimental design of the effects of RF shielded hat on Electroenc Ephalo Gram (EEG) of cameraman

( 2017-01-01)

Hisham N.

;

Rahim H.

;

Malek F.

;

Jusoh M.

;

Fuad F.

;

Romli A.

In this study, the effects of exposure to Radio Frequency Electromagnetic Fields (RF-EMF) on cameraman will be investigated using Electro Encephalo Gram (EEG). There are two hypothesis will be tested which is firstly include the exposure of cameraman to the radio frequency that will affect their brain activity. Second, hypothesis involve the cameraman wearing a RF shielded hat can reduce the effect of exposure to RF-EMF. The 20 healthy cameramen will be involved in this experiment. Well-being and physiological measures of body temperature, blood pressure and heart rate will be obtained. The 2 types of exposure conditions will be conducted (Sham (no exposure) and wireless video-camera exposures). Each exposure will be lasted for 20 min session.

Publication

Mechanical properties of copper ferrite CuFe2O4-polymer composite fabricated using 3D printer

( 2017-01-01)

Lee C.H.

;

Yeoh C.K.

;

Hamzah K.A.

;

Teh P.L.

The effect of speed of powder dispenser on the mechanical properties of ABS-CuFe2O4 composites was studied. The samples in the experiment were printed by a 3D printer which produces three-dimensional objects from the digital file which are built up layer by layer. The amount of filler content added into each sample was controlled by the speed of powder dispenser which is off, low, medium, and high. The properties of pure ABS and composite ABS CuFe2O4 samples were investigated based on the distribution of fillers. Weight percentage (wt%) of filler added into each sample was determined by using thermogravimetric analysis (TGA). Tensile test and Vickers micro hardness were carried out to determine the effect of filler content on mechanical properties. Addition of filler content in ABS matrix slightly decreases the strength of composite from 17.1 MPa to 14.64 MPa.

Publication

On the existence and uniqueness of solutions of fractional order partial integro-differential equations

( 2017-01-01)

Hussain A.K.

;

Fadhel F.S.

;

Rusli N.

;

Yahya Z.R.

The main objective of this paper is to investigate and prove the existence and uniqueness theorems of the solution of nonlinear partial integro-differential equations of fractional order. The theorems of two types for the nonlinear fractional order partial integro-differential equations such as one- and two-dimensional are proved by applying the fixed point theorem of Banach space couple with contraction mapping principle, in which the sufficient conditions are presented in order to ensure the existence and uniqueness of a unique fixed point related to the integro-differential equation in operator form.

Publication

Implementation of on-chip optical interconnect in high speed digital circuit: Two-stage CMOS buffer

( 2017-01-01)

Sallah S.S.B.M.

;

Ali S.H.M.

;

Menon P.S.

;

Juhari N.

;

Islam M.S.

Background: Silicon based photonics has created strong interested in recent years, mainly in optical waveguide interconnects for microelectronic circuits. Materials and Methods: This study reports on the implementation of an Optical Interconnect (OI) waveguide in a digital electronic circuit, a two-stage CMOS buffer. To compare the performance between several waveguide materials with copper interconnect, the optical waveguide was designed and evaluated in OptiBPM to be in a single mode condition. Then, the OI link was simulated in OptiSPICE and their ability as an interconnection was tested in a two-stage CMOS buffer. A propagation delay performance for the whole circuit and for the interconnection only was measured using different material of interconnect. Results: The results showed that the OI minimized the propagation delay in the two-stage CMOS buffer circuit, as well as increased the speed of the integrated circuit. Conclusion: The proposed SOI-based optical waveguide in OI link are able to replace copper based electrical interconnection in electronic circuit technology.

Publication

Analytical method using virtual PM blocks to represent magnet segmentations in surface-mounted PM synchronous machines

( 2017-01-01)

Tiang T.

;

Ishak D.

;

Lim C.

;

Rezal M.

This paper describes an analytical subdomain model to predict the magnetic field distributions in the semi-closed surface-mounted permanent magnet synchronous machines (PMSMs) due to magnet segmentations with radial magnetization (RM). The magnet segments per pole can be virtually represented by finite number of permanent magnet (PM) blocks and Fourier decompositions. The model can also determine the optimum magnet pole-arcs for each segment and the optimum airgap spacing between the segments. The analytical model is then applied to evaluate the performance of a three-phase, 12-slot/8-pole, surface-mounted PMSM having two segmented magnets per pole with RM. With design objective for minimum cogging torque and minimum total harmonic distortion in phase back-emf waveforms, we obtain that the optimum settings are 147.6° elect. for magnet segment pole-arc and 11.2° elect. for airgap spacing between the magnet segments. These analytical results are further compared and validated by 2-D finite element analysis (FEA). Additionally, we also compare the results with those from the optimum magnet pole-arc of one magnet segment per pole machine. It is observed that the cogging torque and total harmonic distortion THDν of the phase back-EMF are significantly reduced by 89% and 25%, respectively, with constraint and assumption that both machines utilize similar total magnet volume.

Publication

Single feed circularly polarized antenna with switchable beam ability

( 2017-01-01)

Jusoh M.

;

Sabapathy T.

;

Rahim H.

;

Shakhirul M.

;

Rahman A.

;

Yasin M.

;

Mat M.

A single feed circularly polarized antenna with the ability to steer the beam has been presented. The presented antenna has successfully achieved circular polarization by ensuring the axial ratio (AR) factor value of less than 3 for 2.4 GHz application. Moreover, by integrating four ideal p-i-n diode switches, the antenna‘s radiation pattern can be directed to the desired direction while suppressing the antenna gain at the unwanted angle without influencing the antenna‘s impedance bandwidth. This antenna is managed to steer the beam with certain p-i-n diode configuration at nine distinguished angle directions. Such microstrip antenna with a simple circular shape is designed on the Taconic substrate with the compact size of 100 mm square. A fully functional antenna design has been developed and tested using CST Microwave Studio. The proposed antenna could be useful for advanced and smart radio application such as 5G and cognitive radio (CR).

Publication

A direct detection of human papillomavirus 16 genomic DNA using gold nanoprobes

( 2017-01-01)

Azizah N.

;

Hashim U.

;

Gopinath S.C.B.

;

Nadzirah S.

Nanoparticles have been investigated as flagging tests for the sensitive DNA recognition that can be utilized as a part of field applications to defeat restrictions. Gold nanoparticles (AuNPs) have been widely utilized due to its optical property and capacity to get functionalized with a mixed bag of biomolecules. This study exhibits the utilization of AuNPs functionalized with single-stranded oligonucleotide (AuNP-oligo test) for fast the identification of Human Papillomavirus (HPV). This test is displayed on interdigitated electrode sensor and supported by colorimetric assay. DNA conjugated AuNP has optical property that can be controlled for the applications in diagnostics. With its identification abilities, this methodology incorporates minimal effort, strong reagents and basic identification of HPV.

Publication

Effect of graphene oxide with controlled stirring time

( 2017-01-01)

Akhair S.

;

Harun Z.

;

Jamalludin M.

;

Shuhor M.

;

Kamarudin N.

;

Yunos M.

;

Ahmad A.

;

Azhar M.

In this study, the effect of graphene oxide (GO) with controlled stirring time was investigated. Five different samples with different stirring time of GO were used at 2 h, 4 h, 6 h, 8 h, and 10 h. The synthesization of GO was conducted using hummers' method by adding graphite, hydroxide sulphuric, permanganate potassium, sodium nitrate, and hydroxide phosphorus. Hydroxide phosphorus was used as main peripheral material to increase the hydrophilic properties in GO performance. Characterization was carried out via XRD, FTIR and contact angle measurement. Results show that the appearance XRD peaks at range between 1,590 cm-1 until 1,750 cm-1 with increase stirring time. However, the lowest contact angle measurement of graphene oxide with high hydrophilicity effect was obviously shown by sample 3.

Publication

Optical tomography verification for single and mixed modalities

( 2017-01-01)

Siti S.Z.

;

Rahim R.A.

;

Fazalul Rahiman M.H.

;

Lee C.K.

;

Amirulah R.

;

Ambar R.

Modelling and experiments are pragmatic methods for verifying the performance of any design. Fundamentally, modelling is the first step to ensure that a design is created according to the desired characteristics. The experimental approach allows the examination of the modelling behaviour in a real environment and the verification of the design's correctness. In this research, the accuracy of an optical tomography system is evaluated by comparing the graph pattern generated through modelling and experimental procedures. Both are conducted in two different projections: single and mixed projections called the parallel beam (PB) projection and the mixed projection of parallel and fan beams left and right (MPFBLR) respectively. The evaluations confirm that the experimental and modelled patterns are consistent. This indicates that the developed optical tomography system has the desired characteristics. In this paper, a novel technique of threshold value, called filtered back projection (FBP) using averaging grouping colour (AGC), is presented. It is found that the more complex the object's location in a pipe, the higher the normalized mean square error (NMSE) and the lower the peak to noise ratio (PSNR).

Publication

Aptamer-based impedimetric determination of the human blood clotting factor IX in serum using an interdigitated electrode modified with a ZnO nanolayer

( 2017-01-01)

Cheen O.C.

;

Gopinath S.C.B.

;

Perumal V.

;

Arshad M.K.M.

;

Lakshmipriya T.

;

Chen Y.

;

Haarindraprasad R.

;

Rao B.S.

;

Hashim U.

;

Pandian K.

This article describes a sensitive impedimetric method for the determination of human blood coagulation factor IX protein (FIX) which is present in extremely low concentration in serum. An interdigitated electrode (IDE) whose surface was layered with zinc oxide was modified with two kinds of probes. One is an antibody, the other an aptamer against FIX. A comparative study between anti-FIX aptamer and anti-FIX antibody showed the aptamer to possess higher affinity for FIX. A sandwich aptamer assay was worked out by using the FIX-binding aptamer on the surface of the IDE. It has a detection limit as low as 10 pM which makes it 4 to 30-fold more sensitive than any other method reported for FIX. Moreover, to practice detection in clinical samples, FIX was detected from the human blood serum by spiking. In our perception, the sensitivity of the ZnO-modified IDE presented here makes it a promising tool for sensing clinically relevant analytes that are present in very low (sub-pM) concentrations. [Figure not available: see fulltext.]

Publication

Novel palm fatty acid functionalized magnetite nanoparticles for magnetic solid-phase extraction of trace polycyclic aromatic hydrocarbons from environmental samples

( 2017-01-01)

Siti Khalijah Mahmad Rozi

;

Hamid Rashidi Nodeh

;

Muhammad Afzal Kamboh

;

Ninie Suhana Abdul Manan

;

Sharifah Mohamad

A novel adsorbent, palm fatty acid coated magnetic Fe3O4 nanoparticles (MNP-FA) was successfully synthesized with immobilization of the palm fatty acid onto the surface of MNPs. The successful synthesis of MNP-FA was further confirmed by X-Ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and Energy dispersive X-Ray spectroscopy (EDX) analyses and water contact angle (WCA) measurement. This newly synthesized MNP-FA was applied as magnetic solid phase extraction (MSPE) adsorbent for the enrichment of polycyclic aromatic hydrocarbons (PAHs), namely fluoranthene (FLT), pyrene (Pyr), chrysene (Cry) and benzo(a)pyrene (BaP) from environmental samples prior to High Performance Liquid Chromatography- Diode Array Detector (HPLC-DAD) analysis. The MSPE method was optimized by several parameters such as amount of sorbent, desorption solvent, volume of desorption solvent, extraction time, desorption time, pH and sample volume. Under the optimized conditions, MSPE method provided a low detection limit (LOD) for FLT, Pyr, Cry and BaP in the range of 0.01-0.05 ng mL–1. The PAHs recoveries of the spiked leachate samples ranged from 98.5% to 113.8% with the RSDs (n = 5) ranging from 3.5% to 12.2%, while for the spiked sludge samples, the recoveries ranged from 81.1% to 119.3% with the RSDs (n = 5) ranging from 3.1% to 13.6%. The recyclability study revealed that MNP-FA has excellent reusability up to five times. Chromatrographic analysis demonstrated the suitability of MNP-FA as MSPE adsorbent for the efficient extraction of PAHs from environmental samples.

Publication

Automatic detection of embolic signal for stroke prevention

( 2017-01-01)

Noor Salwani Ibrahim

;

Ng Yan Duan

;

Dzati Athiar Ramli

;

Haryati Jaafar

Transcranial Doppler (TCD) ultrasound is an essential tool in clinical diagnosis to determine the occurrence of embolism in stroke patients. However, it requires manual attention and the accuracy will deteriorate due to fatigue factor. Instead of depending on human observer as a gold standard to detect the emboli, this study proposes an automated emboli detection system based on three detection methods i.e. time-domain intensity, frequency-domain intensity and time-frequency intensity hybrid. Experimental studies of 240 samples of six data sets were employed. The performance evaluations of each method are measured in term of accuracy percentage and processing speed while human observation is also done as the golden standard for accuracy comparison. The best result is achieved by the time-frequency intensity hybrid method where 90.74 % of the embolic signals and 100 % of the non-embolic signals were successfully identified. The performance of this method is promising as the accuracy achieved by human observation was 87.45 and 100 % for embolic signals and non-embolic signals, respectively.

Publication

Structured light profilometry for designated breast surface coordinate variation analysis

( 2017-01-01)

Vairavan R.

;

Retnasamy V.

;

Mohamad Shahimin M.

;

Sauli Z.

;

Leng L.

;

Wan Norhaimi W.

;

Retnasamy P.

;

Abdullah O.

;

Kirtsaeng S.

Early detection of breast carcinoma is vital for effective treatment option and to enhance the survival rate. Existing breast imaging systems such as ultrasound, mammography, and magnetic resonance imaging (MRI) have been utilized for early detection of breast carcinoma which requires contact with the breast surface. However, these existing methods require contact to the breast surface, which causes discomfort to the test subject. Hence, there is a need for alternative modality, which exhibits a total non-contact nature. Structured light profilometry has developed into a vital system with its application in diverse fields of surface metrology analysis. Therefore, in this work structured light profilometry based on phase shift technique is setup to analyze the surface variation of the breast due to the presence of a lesion in the context of surface tension. The sinusoidal fringe pattern is projected through three step phase shift onto the surface of the breast, and a resulting phase map is produced. Pixel tracing was performed to evaluate the variation of surface changes on the breast based on surface marker coordinates. The comparison was made between breast with lump and breast without a lump. Maiden results have established that the structured light profilometry is capable of detecting breast surface changes at various locations on the breast.

Publication

The Impact of Reaction Parameters on Graphene-like Material Synthesized Using Chemical Vapour Deposition

( 2017-01-01)

Lee H.C.

;

Liu W.W.

;

Chai S.P.

;

Mohamed A.R.

;

Voon C.H.

;

Hashim U.

;

Arshad M.K.M.

;

Adelyn P.Y.P.

;

Huda A.R.N.

;

Kahar S.M.

;

Hidayah N.M.S.

;

Lai C.W.

;

Khe C.S.

The remarkable properties of graphene have directly accelerated the graphene research. Due to its unique and remarkable characteristics, graphene can be potentially used in various applications. Chemical Vapour Deposition (CVD) has been identified as a promising and important method for preparation and production of graphene due to its good film uniformity and large scale production. Herein, we demonstrated that reaction parameters including the reaction duration and reaction temperature could affect the quality, quantity and morphology of synthesized samples. Energy Dispersive X-ray (EDX) results indicated that the carbon content on the graphene-like samples increased with the increasing reaction duration. Scanning electron microscopy (SEM) images showed that thicker carbon clusters were grown when a longer reaction time was used. X-ray diffraction (XRD) pattern indicted carbon existed in the samples synthesized. The comparison between different reaction parameters can assist in selecting the optimum growth parameters of graphene-like samples.

Publication

Improving communication in managing industrialised building system (IBS) projects: Virtual environment

( 2017-01-01)

Pozin M.A.A.

;

Nawi M.N.M.

;

Azman M.N.A.

;

Lee A.

Traditional approaches are still dominant in virtually all construction projects in Malaysia. This was highlighted as the main barrier for further developing the Industrialised Building System (IBS) construction process. Indeed, traditional approaches implemented in IBS have been recognised by several studies as failing to support effective work teams when team processes are disconnected from each other (fragmented), thus failing to produce an effective communication process. Additionally, IBS construction involves large numbers of teams with different expertise and from different organisations, all of which are handled by different numbers of management processes, for instance in planning, manufacturing, transportation, positioning and assembling the structures that involve minimal additional site work. With the increasing demand in building bigger and better buildings and structures, construction projects are becoming more complex to manage by project managers, as they have to manage every single phase by coordinating and monitoring the entire project while at the same time, consider different values and interests from every project team members. Hence, high intensity levels of communication processes involving project team members are importance in order to produce high quality information in decision-making process and conveying instructions to all team members. Regarding the issues of communication practices inside construction projects, this paper explores how communication is applied by the project team management in managing different construction stages inside an IBS construction project with several of stakeholders from diverse locations, and different cultural and organisational backgrounds. Even though a few studies had highlighted communication barriers in the construction field, only a few investigated virtual team practices in the IBS construction industry, especially in Malaysian construction. In this context, preliminary interviews were conducted on several project managers with vast experience in managing IBS construction projects. The content analysis method was used as the technique to ensure the gathered data were comprehensively and accurately analysed. The results showed that most project teams communicated virtually within and among teams for the duration of the project implementation, which the phenomenon is resulting from modern organisational form. There are five categories associated with virtual team work environment, namely distributed area, open discussion, team attitude, communication technology, and reliability of task, all of which are exceptionally pertinent in virtual team, compared to traditional team, work interaction practices.

Publication

Non-linear analysis of Self-Switching Diodes as microwave rectifiers

( 2017-01-01)

Shahrir Rizal Kasjoo

;

Zulfadhli Zailan

;

Sanna Taking

;

Wan Zuki Azman Wan Muhamad

;

Muammar Mohamad Isa

;

Arshad M.

A planar device known as the Self-Switching Diode (SSD) has been demonstrated as a high-speed rectifier, up to terahertz frequencies. The rectifying properties of SSD are dependent on a nonlinear current-voltage characteristic of the device. In this research, the rectification of two SSD rectifiers has been reported and their performances were evaluated. The observed results showed a good agreement with the nonlinear theoretical analysis of both rectifiers by means of a Taylor series which can be utilized in improving the rectifying performance of any diode-based rectifier specifically for diodes with tunable threshold voltage such as SSDs.

Publication

Human breathing classification using electromyography signal with features based on mel-frequency cepstral coefficients

( 2017-01-01)

Ahmad Nasrul Norali

;

Abdullah A.H.

;

Zulkifli Zakaria

;

Norasmadi Abdul Rahim

;

Nataraj S.K.

Typical method on assessing the human breathing characteristics is based on measurements of breathing air parameters. Another possible method for human breathing assessment is through the analysis of respiratory muscles electromyography (EMG) signal. The EMG signal from different breathing task will be analyzed in order to determine the characteristics of the EMG signal pattern. Thus, feature extraction need to be done on the EMG signals. This paper will look into the use of Mel-Frequency Cepstral Coefficients (MFCC) in providing the features for EMG signal. Analysis is done using different data analysis frame sizes. EMG signal classification is done using K-Nearest Neighbour. Results shows that MFCC is a good feature extraction method for this purpose with classification accuracy exceeds more than 90% for data analysis frame size of 2000 ms, 4000 ms, 5000 ms and 10000 ms.

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