Displaying publications 1 - 20 of 250 in total

Abstract:
Sort:
  1. Hasan MM, Faruque MRI, Islam SS, Islam MT
    Materials (Basel), 2016 Oct 13;9(10).
    PMID: 28773951 DOI: 10.3390/ma9100830
    The aim of this paper is to introduce a compact double-negative (DNG) metamaterial that exhibits a negative refractive index (NRI) bandwidth of more than 3.6 GHz considering the frequency from 2 to 14 GHz. In this framework, two arms of the designed unit cell are split in a way that forms a Modified-Z-shape structure of the FR-4 substrate material. The finite integration technique (FIT)-based Computer Simulation Technology (CST) Microwave Studio is applied for computation, and the experimental setup for measuring the performance is performed inside two waveguide ports. Therefore, the measured data complies well with the simulated data of the unit cell at 0-degree and 90-degree rotation angles. The designed unit cell shows a negative refractive index from 3.482 to 7.096 GHz (bandwidth of 3.61 GHz), 7.876 to 10.047 GHz (bandwidth of 2.171 GHz), and 11.594 to 14 GHz (bandwidth of 2.406 GHz) in the microwave spectra. The design also exhibits almost the same wide negative refractive index bandwidth in the major region of the C-band and X-band if it is rotated 90 degrees. However, the novelty of the proposed structure lies in its effective medium ratio of more than 4, wide bandwidth, and compact size.
    Matched MeSH terms: Paper
  2. Borza M, Rambely A, Saraj M
    Sains Malaysiana, 2012;41:1651-1656.
    In this paper, two approaches were introduced to obtain Stackelberg solutions for two-level linear fractional programming problems with interval coefficients in the objective functions. The approaches were based on the Kth best method and the method for solving linear fractional programming problems with interval coefficients in the objective function. In the first approach, linear fractional programming with interval coefficients in the objective function and linear programming were utilized to obtain Stackelberg solution, but in the second approach only linear programming is used. Since a linear fractional programming with interval coefficients can be equivalently transformed into a linear programming, therefore both of approaches have same results. Numerical examples demonstrate the feasibility and effectiveness of the methods.
    Matched MeSH terms: Paper
  3. Prasad, Arun, Kazemian, Sina, Kalantari, Behzad, Bujang B.K. Huat
    MyJurnal
    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.
    Matched MeSH terms: Paper
  4. Hosseingholi Pourasl A, Ariffin SHS, Ahmadi MT, Ismail R, Gharaei N
    Beilstein J Nanotechnol, 2019;10:644-653.
    PMID: 30931206 DOI: 10.3762/bjnano.10.64
    Nanomaterial-based sensors with high sensitivity, fast response and recovery time, large detection range, and high chemical stability are in immense demand for the detection of hazardous gas molecules. Graphene nanoribbons (GNRs) which have exceptional electrical, physical, and chemical properties can fulfil all of these requirements. The detection of gas molecules using gas sensors, particularly in medical diagnostics and safety applications, is receiving particularly high demand. GNRs exhibit remarkable changes in their electrical characteristics when exposed to different gases through molecular adsorption. In this paper, the adsorption effects of the target gas molecules (CO and NO) on the electrical properties of the armchair graphene nanoribbon (AGNR)-based sensor are analytically modelled. Thus, the energy dispersion relation of AGNR is developed considering the molecular adsorption effect using a tight binding (TB) method. The carrier velocity is calculated based on the density of states (DOS) and carrier concentration (n) to obtain I-V characteristics and to monitor its variation in the presence of the gas molecules. Furthermore, the I-V characteristics and energy band structure of the AGNR sensor are simulated using first principle calculations to investigate the gas adsorption effects on these properties. To ensure the accuracy of the proposed model, the I-V characteristics of the AGNR sensor that are simulated based both on the proposed model and first principles calculations are compared, and an acceptable agreement is achieved.
    Matched MeSH terms: Paper
  5. Mukherjee S, Mukhopadhyay S, Pariatamby A, Ali Hashim M, Sahu JN, Sen Gupta B
    J Environ Sci (China), 2014 Sep 1;26(9):1851-60.
    PMID: 25193834 DOI: 10.1016/j.jes.2014.06.029
    Recovery of cellulose fibres from paper mill effluent has been studied using common polysaccharides or biopolymers such as Guar gum, Xanthan gum and Locust bean gum as flocculent. Guar gum is commonly used in sizing paper and routinely used in paper making. The results have been compared with the performance of alum, which is a common coagulant and a key ingredient of the paper industry. Guar gum recovered about 3.86mg/L of fibre and was most effective among the biopolymers. Settling velocity distribution curves demonstrated that Guar gum was able to settle the fibres faster than the other biopolymers; however, alum displayed the highest particle removal rate than all the biopolymers at any of the settling velocities. Alum, Guar gum, Xanthan gum and Locust bean gum removed 97.46%, 94.68%, 92.39% and 92.46% turbidity of raw effluent at a settling velocity of 0.5cm/min, respectively. The conditions for obtaining the lowest sludge volume index such as pH, dose and mixing speed were optimised for guar gum which was the most effective among the biopolymers. Response surface methodology was used to design all experiments, and an optimum operational setting was proposed. The test results indicate similar performance of alum and Guar gum in terms of floc settling velocities and sludge volume index. Since Guar gum is a plant derived natural substance, it is environmentally benign and offers a green treatment option to the paper mills for pulp recycling.
    Matched MeSH terms: Paper*
  6. Abdul Ghapor Hussin, Norli Anida Abdullah, Ibrahim Mohamed
    This paper gives a comprehensive discussion on complex regression model by extending the idea of regression model to circular variables. Various aspect have been considered such as the biasness of parameters, error assumptions and model checking. The advantage of this approach is that it allows the use of usual technique available in ordinary linear regression for the regression of circular variables. The quality of the estimates and the feasibility of the approach were illustrated via simulation. The model was then applied to the wave direction data.
    Matched MeSH terms: Paper
  7. Mohammad Lutfi Othman, Mahmood Khalid Hadi, Noor Izzri Abdul Wahab
    MyJurnal
    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.
    Matched MeSH terms: Paper
  8. Idham Arif Alias
    MyJurnal
    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.
    Matched MeSH terms: Paper
  9. Idham Arif Alias
    A map on a group is not necessarily an automorphism on the group. In this paper we determined the necessary and sufficient conditions of a map on a split metacyclic p-group to be an automorphism, where we only considered 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 considered 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 used the relations and the regularity of the 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.
    Matched MeSH terms: Paper
  10. Fanhui-Zeng, Jianchun-Guo, Yuxuan-Liu
    Sains Malaysiana, 2015;44:1377-1388.
    Hydraulic fracturing becomes more difficult when confronted with a formation of high fracturing pressure. In such formations, acidizing before the main fracturing treatment provide a method to reduce fracture pressure. The aim of this paper was to investigate the evolution of fracture pressure in a wellbore with acidizing. Five experiments were conducted to study the mechanisms of acid damage on reservoir minerals and cementing materials properties. Consequently, a mathematical model to predict fracture pressure with acidizing has been established and verified by field data. The analysis results showed that it is possible to reduce fracture pressure with decreased rock strength and fracture critical stress intensity factor by means of acid damage. Acid damage destroys the crystal structure of mineral particles, breaks the crystalline layers in cementing materials, increases rock porosity and reduces the rock strength. In addition, as the acid concentration, formation temperature and acid treatment time increased, it was useful to reduce fracture pressure in the wellbore. Using the proposed model, we were able to select the optimal acid damage construction parameters to reduce fracture pressure.
    Matched MeSH terms: Paper
  11. Mohd Agos Salim Nasir, Ahmad Izani Md Ismail
    Sains Malaysiana, 2013;42:341-346.
    A high-order uniform Cartesian grid compact finite difference scheme for the Goursat problem is developed. The basic idea of high-order compact schemes is to find the compact approximations to the derivatives terms by differentiating centrally the governing equations. Our compact scheme will approximate the derivative terms by involving the higher terms and reducing the number of grid points. The compact finite difference scheme is given for general form of the Goursat problem in uniform domain and illustrates the performance by applying a linear problem. Numerical experiments have been conducted with the new scheme and encouraging results have been obtained. In this paper we present the compact finite difference scheme for the Goursat problem. With the aid of computational software the scheme was programmed for determining the relative errors of linear Goursat problem.
    Matched MeSH terms: Paper
  12. Muntohar, A.S., Rahman, M.E., Hashim, R., Islam, M.S.
    MyJurnal
    The importance of numerical analysis in investigation of piled embankment over soft soil has been developed since 1990. Several investigators have extended the numerical analysis to model ground improvement using soil-column to support embankment or structures. This paper presents a numerical analysis of the Pulverized Fuel Ash (PFA) column-treated peat and compared with field static-loading test results. Back analysis was performed to determine the material parameters and soil stiffness surrounding soil & soil-column. Two geometrical models were used in this analysis: (a) block (Model A), and (b) column group (Model B). This situation was analyzed using commercially available finite element package PLAXIS 2D ver. 8.2. It is found that both models are reliable to simulate the field static-loading test for column-treated peat. Model B shows a higher stability to failure if compared to Model A.
    Matched MeSH terms: Paper
  13. Faridah Yunos, Kamel Ariffin Mohd Atan, Muhammad Rezal Kamel Ariffin, Mohamad Rushdan Md Said
    MyJurnal
    Elliptic curve cryptosystems (ECC) provides better security for each bit key utilized compared to the RSA cryptosystem. For this reason, it is projected to have more practical usage than the RSA. In ECC, scalar multiplication (or point multiplication) is the dominant operation, namely, computing nP from a point P on an elliptic curve, where n is an integer defined as the point resulting from adding P + P + ... + P, n times. However, for practical uses, it is very important to improve the efficiency of the scalar multiplication. Solinas (1997) proposes that the τ-adic Non-Adjacent Form (τ-NAF) is one of the most efficient algorithms used to compute scalar multiplications on Anomalous Binary curves. In this paper, we give a new property (i.e., Theorem 1.2) of τ-NAF(n) representation for every length, l. This is useful for evaluating the maximum and minimum norms occurring among all length-l elements of Z(τ). We also propose a new cryptographic method by using randomization of a multiplier n to nr an element of Z(τ). It is based on τ-NAF. We focused on estimating the length of RTNAF(nr) expansion by using a new method.
    Matched MeSH terms: Paper
  14. Ebrahim Jahanshiri, Taher Buyong, Abdul Rashid Mohd. Shariff
    MyJurnal
    Mass valuation of properties is important for purposes like property tax, price indices construction, and understanding market dynamics. There are several ways that the mass valuation can be carried out. This paper reviews the conventional MRA and several other advanced methods such as SAR, Kriging, GWR, and MWR. SAR and Kriging are good for modeling spatial dependence while GWR and MWR are good for modeling spatial heterogeneity. The difference between SAR and Kriging is the calculation of weights. Kriging weights are based on the spatial dependence or so called the semi-variogram analysis of the price data whereas the weights in SAR are based on the spatial contiguity between the sample data. MWR and GWR are special types of regression where study region is subdivided into local sections to increase the accuracy of prediction through neutralizing the heterogeneity of autocorrelations. MWR assigns equal weights for observations within a window while GWR uses distance decay functions. The merits and drawbacks of each method are discussed.
    Matched MeSH terms: Paper
  15. Hao, Lim Zhen, Hikmat Said Al-Salim, Norida Ridzuan
    MyJurnal
    The continuous depletion of global oil reserves with the propensity for light distillates
    propels the oil and gas industry to explore heavier fractions of crude oils with significant
    amount of paraffin waxes. However, the precipitation and deposition of waxes during the
    transportation of these waxy crude oils in the pipelines contribute to several issues, such as
    the flowability reduction, excessive pumping cost, and wax gel formation, that adversely
    affect the supposedly steady offshore oil production. As a result, substantial resources are
    expended to resolve these flow assurance problems. The wax inhibitors and pour point
    depressants are developed and modified to meet the wax remediation criteria. Essentially,
    the wax crystals are formed through the nucleation, growth, and agglomeration processes,
    while the deposition of these waxes occurs via molecular diffusion and shear dispersion.
    The wax inhibitors are able to control the growth of wax crystals through nucleation, cocrystallization,
    adsorption, and dispersion interactions. This paper particularly assessed
    the following compounds: (1) polymeric wax inhibitors, (2) nano-hybrid pour point
    depressants, (3) organic solvents, and
    (4) surfactants. Given the significance of
    these compounds in the deposition and
    precipitation of waxes, it is imperative to
    comprehensively explore the types and
    nature of these compounds and their recent
    applications as well as to critically assess
    their strengths and drawbacks, which were
    addressed in this paper. Furthermore, the
    challenges of using these compounds and the factors that govern their efficiencies were also discussed. Accordingly, the carbon
    length and the molecular weight of both paraffin waxes and wax inhibitors are among the
    most influential factors.
    Matched MeSH terms: Paper
  16. C.H. Asmawati, M.R. Ahmad Ruslan, Y. Zulkiflee, M.N.N. Husna
    ASM Science Journal, 2013;7(2):113-117.
    MyJurnal
    Nowadays, construction and demolition waste has become a major issue to environmental problems faced by many countries. This concern comes from the inefficiencies of waste management which includes the waste generated from construction and demolition activities. In Malaysia, there is a lack of database records on construction waste and this has affected proper management planning of the waste. As there is a lack of policy on construction waste management, control on construction waste disposal is very hazy and this has aggravated environmental problems and exhausted landfill usage and increased illegal dumping. This paper reviews the critical issues on construction waste management and also discusses several estimation models on construction waste generation from several countries. Based on the review, most of the countries faced problems regarding construction waste management and the models developed were considered as one of the methods which could be adopted for better management of construction wastes.
    Matched MeSH terms: Paper
  17. Roslina Mohammad, Zamree Amin, Norazli Othman
    MyJurnal
    The aim of this paper is to identify, review and carry out comparison to seven guidelines where the main focus is on its risk
    assessment elements related to confined space activities. This is due to lack of the specific approach of the Legislation for confined
    space such as entry procedure requirements, risk assessment method, existing practice of risk assessment is too general and additional
    references are required for conducting risk assessment which would lead to poor response from industries. The selected guidelines will
    be summarized on its requirements, followed by a review of each guideline and finally the comparison of Legislations will be carried
    out. The results from the study would be used as a contribution factor to promote an ideal method in developing an effective risk
    assessment tools for working safely in confined space. Furthermore, several literatures which have been referred could give additional
    input for developing the risk assessment tools.
    Matched MeSH terms: Paper
  18. Chan KW, Tan GH, Wong RC
    Sci Justice, 2012 Sep;52(3):136-41.
    PMID: 22841136 DOI: 10.1016/j.scijus.2012.04.006
    Statistical classification remains the most useful statistical tool for forensic chemists to assess the relationships between samples. Many clustering techniques such as principal component analysis and hierarchical cluster analysis have been employed to analyze chemical data for pattern recognition. Due to the feeble foundation of this statistics knowledge among novice drug chemists, a tetrahedron method was designed to simulate how advanced chemometrics operates. In this paper, the development of the graphical tetrahedron and computational matrices derived from the possible tetrahedrons are discussed. The tetrahedron method was applied to four selected parameters obtained from nine illicit heroin samples. Pattern analysis and mathematical computation of the differences in areas for assessing the dissimilarity between the nine tetrahedrons were found to be user-convenient and straightforward for novice cluster analysts.
    Matched MeSH terms: Paper
  19. Ellappan, S., Khoo Michael, B. C.
    MyJurnal
    A multivariate control chart is a common tool used for monitoring and controlling a process whose quality is determined by several related variables. The objective of this study is to compare the performances of the multivariate exponentially weighted moving average (MEWMA) and the multivariate synthetic T2 control charts, for the case of a multivariate normally distributed process. A comparative study is made based on the average run length (ARL) performances of the control charts, using the simulation method, in order to identify the chart having the best performance in monitoring the process mean vector. The performances of the two charts, for different sample sizes and correlation coefficients, are presented in this paper. It was found that the MEWMA chart outperformed synthetic T2 chart for small shifts but the latter prevailed for moderate shifts. Both charts performed equally well for larger shifts. In addition, the performances of both MEWMA and synthetic T2 charts were found to be influenced by sample size and correlation coefficient. The two charts’ performances improved as the sample size and correlation coefficient increased for small and moderate shifts, but the charts’ performances did not depend on sample size and correlation coefficient when the shift was large.
    Matched MeSH terms: Paper
  20. Low A, Bansal V
    Biomed Imaging Interv J, 2010 01 01;6(1):e9.
    PMID: 21611068 DOI: 10.2349/biij.6.1.e9
    Many papers have been written on the synthesis of gold nanoparticles but very few included pictures of the process, and none of them used video to show the whole process of synthesis. This paper records the process of synthesis of gold nanoparticles using video clips. Every process from cleaning of glassware, an important step in the synthesis of metallic nanoparticles, to the dialysis process is shown. It also includes the preparation of aqua regia and the actual synthesis of gold nanoparticles. In some papers, the dialysis process was omitted, but in this paper, it is included to complete the whole process as it is being used for purification.
    Matched MeSH terms: Paper
Filters
Contact Us

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links