Displaying publications 1 - 20 of 811 in total

  1. Fathinul Fikri, A.S., Noraini Sarina, A., Shahrin, S., Abdul Jalil, N.
    Colo-colic intussusception is a rare manifestation of a primary tumour in an adult patient. This article
    aims to document the rarity of colo-colic intussusception features on the 18 FDG- PET-CT in a patient
    with primary colonic carcinoma. An 18 FDG-PET-CT was performed for the purpose of pretreatment
    staging of a colonic carcinoma in a 61-year-old man following a diagnostic colosnoscopic biopsy. He
    presented with abdominal distension and peri-rectal bleeding for a month. The fused 18 F-FDG PET-CT
    image revealed an FDG-avid mass in the left hemicolon showing a rim of FDG avidity denoting the head
    of intussusceptum. There are also multiple FDG-avid nodules seen along the anti-mesenteric colonic fat
    suspicious for lymph nodes metastasis. Debulking of tumour revealed a mucinous adenocarcinoma of
    colon with a metastatic lymph node. 18 FDG PET-CT features of intussusception in colonic carcinoma
    have never been described before. It can potentially become a preferred diagnostic tool in delineating a
    potential tumour mass within the intussusceptions that help improve prognosis in patients with malignancy.
  2. Wan Ahmad Hazim, Nur Hidayah Aeshah Ng, Salleha Khalid
    Minimally invasive surgery results in faster recovery. The objective of this study is to identify criteria for the feasibility of 24-hour discharge post laparoscopic ovarian cystectomy. This is a prospective cross-sectional study that was carried out at the Obstetrics and Gynaecology Department in Putrajaya Hospital between 1 January and 31 December, 2016. The inclusion criteria were: age between 15 and 45, no comorbidities, no family history of malignancy, BMI of less than 30, mass size less than 18 weeks, single uninoculated simple cyst and no ascites. The exclusion criteria were post-menopause women, known medical illness, family history of malignancy, mass size more than 18 weeks, multiloculated or bilateral ovarian cyst, presence of solid area within the cyst and ascites. The sample size was calculated to be 14. A total of 16 participants were identified. Results showed that using the Visual Analogue Score (VAS), the mean pain score post operatively in the first six hours, 24 hours, 48 hours, two weeks and three months were 3.67, 2.57, 0.5, 0 and 0, respectively. Two of the subjects experienced post-operative nausea and vomiting, one had urinary tract infection and one had minor bleeding from the surgical site. All the participants were discharged within 24 hours post-operatively. There was no readmission. In conclusion, 24-hour discharge post laparoscopic cystectomy is safe and feasible. Factors determining the success must be adhered to closely to ensure a good and satisfactory outcome. This research did not receive any specific grant from funding agencies in the public, commercial or not-for-profit sectors.
  3. Dinaagaren Selvadurai, Roslina M. Sidek, Khalid Al-Hussaini, Borhanuddin M. Ali
    Digital predistortion is one of the most widely used techniques to linearize a power amplifier (PA) to
    reduce the error vector magnitude (EVM) distortion and spectral regrowth. By far, the lookup table (LUT) predistorters are most frequently used scheme to mitigate the effects of non-linear power amplifier. In this paper, a new algorithm of joint-polynominal LUT predistorter which attains the best linearization performance is proposed. The algorithm employs the hermite interpolation LUT, which has a higher accuracy of interpolation. Simulation results show that the proposed method provides a better rejection of EVM distortion and an improvement of 30-40% of adjacent channel leakage ratio (ACLR) for the wideband code division multiple access at a minimal memory usage.
  4. Abdu Masanawa Sagir, Saratha Sathasivam
    Medical diagnosis is the process of determining which disease or medical condition explains a person’s determinable signs and symptoms. Diagnosis of most diseases is very expensive as many tests are required for predictions. This paper aims to introduce an improved hybrid approach for training the adaptive network based fuzzy inference system (ANFIS). It incorporates hybrid learning algorithms least square estimates with Levenberg-Marquardt algorithm using analytic derivation for computation of Jacobian matrix, as well as code optimisation technique, which indexes membership functions. The goal is to investigate how certain diseases are affected by patient’s characteristics and measurement such as abnormalities or a decision about the presence or absence of a disease. In order to achieve an accurate diagnosis at this complex stage of symptom analysis, the physician may need efficient diagnosis system to classify and predict patient condition by using an adaptive neuro fuzzy inference system (ANFIS) pre-processed by grid partitioning. The proposed hybridised intelligent technique was tested with Statlog heart disease and Hepatitis disease datasets obtained from the University of California at Irvine’s (UCI) machine learning repository. The robustness of the performance measuring total accuracy, sensitivity and specificity was examined. In comparison, the proposed method was found to achieve superior
    performance when compared to some other related existing methods.
  5. Ahmad, Syukri Mohamad, Norman, Mariun
    Cascaded multilevel inverters are popular in fields such as oil and gas, power supply installations, and
    power quality devices. While there are many advantages of the cascaded multilevel inverter, its main
    disadvantage is the need for large numbers of multiple dc sources. In order to reduce total harmonics
    distortion (THD) of the output voltage waveform, the amount of output voltage level must be increased,
    hence the higher number of dc sources. This essentially complicated the inverter design, as most converter
    transform only one voltage source to another. In this paper a cascaded multilevel inverter topology with a
    single dc source is discussed. The topology is based on capacitors instead of cells as the multiple voltage
    sources. The cascaded multilevel inverter topology validity and functionality is verified by the Matlab
    Simulink simulation of a 100W and 1kW aircraft single phase 41-level inverter.
  6. Prasad, Arun, Kazemian, Sina, Kalantari, Behzad, Bujang B.K. Huat
    In the literature, several methods of ground improvement have been presented including compacted stone columns. The bearing capacity of the granular column is governed mainly by the lateral confining pressure mobilized in the soft soil to restrain or prevent bulging of the granular column. Therefore, the technique becomes unfeasible in peat that does not provide sufficient lateral confinement. This condition can be overcome by encasing the stone column with geogrid. This paper investigates the performance of the geogrid encased vibrocompacted stone column in peat. This study was carried out using PLAXIS software equipped with unit cell concept. The peat was modelled using soft soil model and the stone column using Mohr-Coulomb soil model, respectively. The geogrid was modelled using the geogrid option and could take only tensile force. The results indicate that the geogrid encased stone column can take much higher load in comparison to ordinary stone columns as the stiffness of the column increases. Meanwhile, the length of encasement also varied and it was observed that it was very effective up to about two times the diameter of the column. It also increased the column stiffness, and therefore led to a significant strain reduction. It was also observed that the columns at a spacing of three times the diameter are very effective. The results presented here can be used by the geotechnical engineers to design the geogrid reinforced stone column based on the strength of the soil, diameter of the column, spacing of the columns and stiffness of the geogrid.
  7. Zahari Taha, Ruhaizin Sulaiman
    The physical strength of the elderly aged above 60 years is typically 10 to 30% less than the young adult population of ages between 25 to 35 years. This reduction of strength has a strong impact on the activity of the daily living (ADL) of the elderly population. There has been little research done studying on the physical strength of the elderly population in Malaysia. The objective of this study was to determine the static strength of the elderly population in Malaysia. In particular, the grip and pinch strength were investigated as these two static strengths are extensively used in their instrumental activity of daily living (IADL). The results were then compared to the strength of the university students. A total of 30 subjects (15 males and 15 females) participated in the study. Their age ranged between 60 to 83 years, with the mean of age of 67.1 years. The comparison group comprised a total of 30 university students (20 male, 10 female) aged between 23 to 24 years, with the mean of age of 23.2 years. Grip and pinch strengths of both groups were measured and analysed using a descriptive statistics. It was found that the elderly male subjects are stronger in both strength measurements than their female counterpart. The 95th percentile of the female grip strength was slightly lower than that of the male while the male pinch strength was 31.07% higher. It was also found that the male students had higher strengths compared to the females. The grip strength of the elderly was 30.66% lower than the university student, while their pinch strength was 13.42% lower. Both static strengths of the elderly were found to be lower than those of the university students. This supported the research hypotheses postulating that the static strength had a negative correlation with age. In terms of gender differences, the male subjects were found to be stronger than the females.
  8. Soon, C.K., Zaini, Z., Mohd Ujang, A., Nagapan, S., Abdullah, A.H., Hasmori, M.F., et al.
    The building sector consumes about forty percent of world energy, making energy efficiency in existing buildings an important issue. This study has been undertaken to investigate energy consumption of a building that has been redesigned to incorporate energy efficient features. It was found that the introduction of energy efficient features has helped to achieve savings up to 46% of the total spent on energy particularly based on electricity bills.
  9. Azizan Yatim
    Malaysian Studies is a compulsory course for international undergraduate students in Malaysia. The
    subject comprises Malaysian history, its governance and administration system. Due to different sociocultural
    backgrounds and histories, most, if not all, international students, struggled with this subject.
    This research project aims to create, implement and evaluate a mobile application (app) as a catalyst for
    mobile learning (m-learning) for one particular topic of the Malaysian Studies course. The increased
    use of technology in learning environments has changed instructional approaches by making it more
    accessible and essentially, more student-centered. Using a design-based research approach, the mobile
    app is aimed to guide students to write their own notes to assist in deeper understanding of the subject.
    The mobile app was also reviewed by users to gauge its effectiveness and ease of use. Findings from the
    tests showed the potential to structure the students’ learning from the topic. From the research, there are
    a few improvements and suggestions that could be implemented for similar future studies and projects.
  10. Maryam Mirzaei, Jasronita Jasni, Hashim Hizam, Noor Izzri Abdol Wahab, Ehsan Moazami
    In this paper, a multi-objective analytical method to evaluate the impacts of optimal location and sizing
    of distributed generation is presented. This method is based on an analysis of the exact loss formula and
    continuous power flow in a radial distribution system. Based on two methods of analysis, power loss
    and weakest voltage buses and lines are calculated and then the optimal size of distributed generation
    is determined. After that, by considering the minimum power losses and the maximisation of voltage
    stability, the proposed index determines and ranks positions to decide the optimal distributed generation
    location in the system. This method allows us to find the best places and size to connect a number of
    distributed generation units by optimising the objective functions. The simulation results were obtained
    using a 33-bus radial distribution system to determine the location and size of the distributed generation
    units. The results show the effectiveness of voltage profile improvement, loading factor improvement
    and power loss reduction. Further, the problems of a single objective function and the placement of the
    distributed generation unit using analytical methods are solved by the proposed approach.
  11. Farah N.A. Abd. Aziz, Sani M.B., Noor Azline M.N., Jaafar M.S.
    An incorporation of waste tyre particles in concrete has been established to produce a green concrete.
    However, despite its advantages, strength reduction is an obvious handicap. To improve the strength,
    pre-treatments of the waste tyre particles and addition of Oil Palm Fruit Fibre (OPFF) were chosen and
    reported in this study. The addition of OPFF was to influence the internal structure in order to improve
    shrinkage and other strength properties. Performance of the composites in compressive, split tensile and
    flexural strengths, as well as shrinkage and microstructure were observed. Results showed better behaviour
    of the treated tyre crumb mortar rather compared to the untreated tyre, with the replacement of up to 40%
    by volume of the treated tyre crumb particles and 0.5- 1.0% OPFF addition by mass of cement content.
  12. Taufiq-Yap, Y. H., Ong, P. S., Zainal, Z.
    In this work, 10 mol% yttrium-doped ceria powders, Ce0.9Y0.1O1.95, were synthesised using a new mechanical technique, mechanochemical reaction, in which both impact action and shearing forces were applied for efficient fine grinding, subsequently leading to higher homogeneity of the resultant powders. Ce0.9Y0.1O1.95 prepared using this new technique was systematically compared with a sample of the same prepared using conventional solid-state methodology. X-ray diffraction analysis showed all prepared samples were single phase with a cubic fluorite structure. Generally, Y2O3-doped CeO2 electrolytes prepared by mechanochemical reactions were stable at a lower temperature (1100 °C) compared with a sample of the same synthesised using the conventional solid-state method. Characterisations using differential thermal analysis (DTA) and thermogravimetric analysis (TGA) showed no thermal changes and phase transitions, indicating all materials were thermally stable. The electrical properties of the samples investigated by AC impedance spectroscopy in the temperature range 200–800 ˚C are presented and discussed. Scanning electron microscopy (SEM) was used to study the morphology of the materials. Fine-grained powders with uniform grain-size distribution were obtained from the mechanochemical reaction.
  13. Hong, Choon Ong, Tilahun, Surafel Luleseged, Tang, Suey Shya
    Many studies have been carried out using different metaheuristic algorithms on optimisation problems in various fields like engineering design, economics and routes planning. In the real world, resources and time are scarce. Thus the goals of optimisation algorithms are to optimise these available resources. Different metaheuristic algorithms are available. The firefly algorithm is one of the recent metaheuristic algorithms that is used in many applications; it is also modified and hybridised to improve its performance. In this paper, we compare the Standard Firefly Algorithm, the Elitist Firefly Algorithm, also called the Modified Firefly Algorithm with the Chaotic Firefly Algorithm, which embeds chaos maps in the Standard Firefly Algorithm. The Modified Firefly Algorithm differs from the Standard Firefly Algorithm in such a way that the global optimum solution at a particular iteration will not move randomly but in a direction that is chosen from randomly generated directions that can improve its performance. If none of these directions improves its performance, then the algorithm will not be updated. On the other hand, the Chaotic Firefly Algorithm tunes the parameters of the algorithms for the purpose of increasing the global search mobility i.e. to improve the attractiveness of fireflies. In our study, we found that the Chaotic Firefly Algorithms using three different chaotic maps do not perform as well as the Modified Firefly Algorithms; however, at least one or two of the Chaotic Firefly Algorithms outperform the Standard Firefly Algorithm under the given accuracy and efficiency tests.
  14. Zuber, M., Hisham, M.S.B., Nasir, N.A.M., Basri, A.A., Khader, S.M.A.
    This paper is a Computational Fluid Dynamics (CFD) study of the performance of a jet engine annular
    combustor that was subjected to various loading conditions. The aim is to comprehend the effect of
    various genuine working conditions on ignition and emission performance. The numerical models utilized for fuel ignition is the feasible k-ω model for turbulent stream, species transport (aviation fuel and air) with eddy-dissipation reaction modelling and pollution model for nitrogen oxides (NOX) emission. The results obtained confirm the findings described in the literature.
  15. Esam Taha Yassen, Anas Arram, Masri Ayob, Mohd Zakree Ahmad Nazri
    Police patrol routing problem (PPRP) attracts researchers’ attention especially on artifitial inteligence. The challenge here is that a limited number of patrols cover a wide range of area that includes several hotspots. In this study, a new model for PPRP is proposed simulating the Solomon’s benchmark for vehicle routing problem with time windows. This model can solve this problem by maximising the coverage of hotspots with frequencies of high priority locations while ensuring the feasibility of routes. Two constructive greedy heuristics are developed to generate the initial solution of the PPRP: highest priority greedy heuristic (HPGH) and nearest neighbour greedy heuristic (NNGH). Experimental results show that the simulated Solomon’s benchmark is suitable to represent PPRP. In addition, results illustrate that NNGH is more efficient to construct feasible solution than HPGH.
  16. Mohammad Lutfi Othman, Mahmood Khalid Hadi, Noor Izzri Abdul Wahab
    Special Protection Schemes (SPSs), are corrective action schemes that are designed to protect power
    systems against severe contingency conditions. In planning of SPSs, protecting transmission network from
    overloading issue due to critical situations has become a serious challenge which needs to be taken into
    account. In this paper, a Special Protection and Control Scheme (SPCS) based on Differential Evolution
    (DE) algorithm for optimal generation rescheduling has been applied to mitigate the transmission line
    overloading in system contingency conditions. The N-1 contingency has been performed for different
    single line outages under base and increased load in which generation rescheduling strategy has been
    undertaken to overcome the overloading problem. Simulation results are presented for both pre-and
    post system emergency situations. The IEEE 30-bus test system was utilised in order to validate the
    effectiveness of the proposed method.
  17. Idham Arif Alias
    A map on a group is not necessarily an automorphism on the group. In this paper we study the necessary and sufficient conditions for a map on a non-split metacyclic p-group to be an automorphism, where we only consider p as an odd prime number. The metacyclic group can be defined by a presentation and it will be beneficial to have a direct relation between the parameters in the presentation and an automorphism of the group. We consider the action of an automorphism on the generators of the group mentioned. Since any element of a metacyclic group will be mapped to an element of the group by an automorphism, we can conveniently represent the automorphism in a matrix notation. We then use the relations and the regularity of the non-split metacyclic p-group to find conditions on each entry of the matrix in terms of the parameters in its presentation so that such a matrix does indeed represent an automorphism.
  18. Mansa, Rachel Fran, Sipaut, Coswald Stephen, Suhaimi Md.Yasir, Dayou, Jedol, Joannes, Costantine
    The feasibility study on Chlorella sp. lipid extraction using an electrolysis treatment (ET) as
    pre-treatment was investigated. Stainless steel was used as the anode and cathode material.
    The ET method was conducted in a batch or continuous system with or without air aeration
    and recycling flow. The total lipid in Chlorella sp. AWET and AWET were not analysed due to
    small sample volume. Approximately same amount of lipids were attained from Chlorella
    sp. BWOET (7.97 ± 0.43% glipid/gdry wt) and BWET (7.95 ± 0.37% glipid/gdry wt) if treated at 5 V/cm
    and aerated at 16.7 μm3/s for 1800s. Whereas, if Chlorella sp. was treated at 13 V/cm and
    aerated at 16.7 μm3/s for 1800 s, the total lipid obtained in Chlorella sp. CWOET (8.18 ± 0.49%
    glipid/gdry wt) was 1.13-fold higher than CWET (7.22 ± 0.47% glipid/gdry wt). Meanwhile under
    semi-continuous system, similar pattern of
    result was achieved in Chlorella sp. DWOET
    (8.58 ± 0.49% glipid/gdry wt) with 1.11-fold
    higher than DWET (7.72 ± 0.54% glipid/gdry
    wt), if treated at 14 V/cm and recycled at 2.3
    μm3/s for 3000s. This corresponded to lipid
    oxidation that might have occurred during
    the ET method. The fatty acid methyl ester
    (FAME) composition of Chlorella sp. DWOET
    and DWET contained predominantly methyl
    linolenate (C18:3) and methyl palmitate (C16:0). The concentrations of methyl palmitate attained in Chlorella sp. DWOET and DWET
    were 0.049 ± 0.005 g/m3 and 0.045 ± 0.005 g/m3, respectively.
  19. Syazreen Niza Shair, Nur Azhani Zolkifli, Nur Faiqah Zulkefli, Azizah Murad
    The functional data model has recently received increasing attention particularly in their application to mortality forecasting. The advantage of this method over the well-known Lee-Carter model is the ability to treat the underlying process as functional, and provide estimations that are robust to outliers. This research investigates the accuracy of functional data approach in estimating the mortality rates and life expectancy at births in developing countries including Malaysia, Indonesia, Thailand and Singapore. The functional data method was applied to these countries’ mortality data, and the out-sample forecast errors showed that, in terms of overall, the functional data model was more accurate than that of the original Lee-Carter model for males and females. The results provide evidence that the functional model is accurate to forecast the life expectancy at births for developing countries.
  20. Mokhtar, M., Shuib, A., Mohamad, D.
    Portfolio optimisation is one of the most crucial issues in investment decision-making and has received considerable attention from researchers and practitioners. Traditionally, the portfolio optimisation models are formulated based on the assumption that investors have complete information on the distribution of random returns. However, in real life case, this is not possible since decisions have to be made under uncertainty. This paper deals with a fuzzy portfolio optimisation problem in which returns and turnover rates of securities are represented by fuzzy variables. A goal programming model is proposed to optimise three objectives: maximisation of portfolio return, maximisation of liquidity and minimisation of the portfolio risk. The cardinality constraints, floor and ceiling constraints are also taken into consideration. Finally, a numerical experiment using real data is conducted to demonstrate the applicability of the model.
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