Displaying publications 1 - 20 of 88 in total

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  1. Yusrina Andu, Muhammad Hisyam Lee, Zakariya Yahya Algamal
    MATEMATIKA, 2019;35(2):139-147.
    MyJurnal
    The fast-growing urbanization has contributed to the construction sector be- coming one of the major sectors traded in the world stock market. In general, non- stationarity is highly related to most of the stock market price pattern. Even though stationarity transformation is a common approach, yet this may prompt to originality loss of the data. Hence, the non-transformation technique using a generalized dynamic principal component (GDPC) were considered for this study. Comparison of GDPC was performed with two transformed principal component techniques. This is pertinent as to observe a larger perspective of both techniques. Thus, the latest weekly two-years observations of nine constructions stock market price from seven different countries were applied. The data was tested for stationarity before performing the analysis. As a re- sult, the mean squared error in the non-transformed technique shows eight lowest values. Similarly, eight construction stock market prices had the highest percentage of explained variance. In conclusion, a non-transformed technique can also present a better result outcome without the stationarity transformation.
  2. Yusof, F. M., Md. Ismail, A. I. B., Abu Hasan, Y.
    MATEMATIKA, 2018;34(2):205-226.
    MyJurnal
    Hantaviruses are etiological agents of zoonotic diseases and certain other dis-
    eases, which pose a serious threat to human health. When rodent and predator popula-
    tions share in an ecology, the competitive force of the populations can lead to a reduction
    or elimination of a hantavirus outbreak. The effect of the predator eliminating rodents
    and predator populations that tends to reduce or eliminate hantavirus infection is investi-
    gated. The existence of several equilibrium points of the model is identified and local and
    global stabilities of the model at these equilibrium points are analysed in detail. Numerical
    simulations are carried out to illustrate our model results.
  3. Yahaya Shagaiya Daniel, Zainal Abdul Aziz, Zuhaila Ismail, Faisal Salah
    MATEMATIKA, 2018;34(2):393-417.
    MyJurnal
    Analyzed the effects of thermal radiation, chemical reaction, heat gener-
    ation/absorption, magnetic and electric fields on unsteady flow and heat transfer of
    nanofluid. The transport equations used passively controlled. A similarity solution is
    employed to transformed the governing equations from partial differential equations to
    a set of ordinary differential equations, and then solve using Keller box method. It was
    found that the temperature is a decreasing function with the thermal stratification due to
    the fact the density of the fluid in the lower vicinity is much higher compared to the upper
    region, whereas the thermal radiation, viscous dissipation and heat generation enhanced
    the nanofluid temperature and thermal layer thickness.
  4. Wan, Heng Fong, Nurul Izzaty Ismail
    MATEMATIKA, 2018;34(1):59-71.
    MyJurnal
    In DNA splicing system, the potential effect of sets of restriction enzymes and
    a ligase that allow DNA molecules to be cleaved and re-associated to produce further
    molecules is modelled mathematically. This modelling is done in the framework of formal
    language theory, in which the nitrogen bases, nucleotides and restriction sites are modelled
    as alphabets, strings and rules respectively. The molecules resulting from a splicing system
    is depicted as the splicing language. In this research, the splicing language resulting from
    DNA splicing systems with one palindromic restriction enzyme for one and two (nonoverlapping)
    cutting sites are generalised as regular expressions.
  5. Wan Heng Fong, Nurul Izzaty Ismail, Nor Haniza Sarmin
    MATEMATIKA, 2019;35(301):1-14.
    MyJurnal
    Abstract In DNA splicing system, DNA molecules are cut and recombined with the presence of restriction enzymes and a ligase. The splicing system is analyzed via formal language theory where the molecules resulting from the splicing system generate a language which is called a splicing language. In nature, DNA molecules can be read in two ways; forward and backward. A sequence of string that reads the same forward and backward is known as a palindrome. Palindromic and non-palindromic sequences can also be recognized in restriction enzymes. Research on splicing languages from DNA splicing systems with palindromic and non-palindromic restriction enzymes have been done previously. This research is motivated by the problem of DNA assembly to read millions of long DNA sequences where the concepts of automata and grammars are applied in DNA splicing systems to simplify the assembly in short-read sequences. The splicing languages generated from DNA splicing systems with palindromic and non- palindromic restriction enzymes are deduced from the grammars which are visualised as automata diagrams, and presented by transition graphs where transition labels represent the language of DNA molecules resulting from the respective DNA splicing systems.
  6. Vincent Daniel David, Arifah Bahar, Zainal Abdul Aziz
    MATEMATIKA, 2018;34(101):179-187.
    MyJurnal
    The flow of water over an obstacle is a fundamental problem in fluid mechanics.
    Transcritical flow means the wave phenomenon near the exact criticality. The transcriti-
    cal flow cannot be handled by linear solutions as the energy is unable to propagate away
    from the obstacle. Thus, it is important to carry out a study to identify suitable model
    to analyse the transcritical flow. The aim of this study is to analyse the transcritical
    flow over a bump as localized obstacles where the bump consequently generates upstream
    and downstream flows. Nonlinear shallow water forced Korteweg-de Vries (fKdV) model
    is used to analyse the flow over the bump. This theoretical model, containing forcing
    functions represents bottom topography is considered as the simplified model to describe
    water flows over a bump. The effect of water dispersion over the forcing region is in-
    vestigated using the fKdV model. Homotopy Analysis Method (HAM) is used to solve
    this theoretical fKdV model. The HAM solution which is chosen with a special choice
    of }-value describes the physical flow of waves and the significance of dispersion over a
    bump is elaborated.
  7. Ummu Atiqah Mohd Roslan
    MATEMATIKA, 2018;34(1):13-21.
    MyJurnal
    Markov map is one example of interval maps where it is a piecewise expanding
    map and obeys the Markov property. One well-known example of Markov map is the
    doubling map, a map which has two subintervals with equal partitions. In this paper, we
    are interested to investigate another type of Markov map, the so-called skewed doubling
    map. This map is a more generalized map than the doubling map. Thus, the aims of this
    paper are to find the fixed points as well as the periodic points for the skewed doubling
    map and to investigate the sensitive dependence on initial conditions of this map. The
    method considered here is the cobweb diagram. Numerical results suggest that there exist
    dense of periodic orbits for this map. The sensitivity of this map to initial conditions is
    also verified where small differences in initial conditions give different behaviour of the
    orbits in the map.
  8. Tiaw, Kah Fookand, Zarina Bibi Ibrahim
    MATEMATIKA, 2017;33(2):215-226.
    MyJurnal
    In this paper, we study the numerical method for solving second order Fuzzy
    Differential Equations (FDEs) using Block Backward Differential Formulas (BBDF)
    under generalized concept of higher-order fuzzy differentiability. Implementation of
    the method using Newton iteration is discussed. Numerical results obtained by BBDF
    are presented and compared with Backward Differential Formulas (BDF) and exact
    solutions. Several numerical examples are provided to illustrate our methods.
  9. Suhartono, Prastyo, Dedy Dwi, Kuswanto, Heri, Muhammad Hisyam Lee
    MATEMATIKA, 2018;34(1):103-111.
    MyJurnal
    Monthly data about oil production at several drilling wells is an example of
    spatio-temporal data. The aim of this research is to propose nonlinear spatio-temporal
    model, i.e. Feedforward Neural Network - VectorAutoregressive (FFNN-VAR) and FFNN
    - Generalized Space-Time Autoregressive (FFNN-GSTAR), and compare their forecast
    accuracy to linearspatio-temporal model, i.e. VAR and GSTAR. These spatio-temporal
    models are proposed and applied for forecasting monthly oil production data at three
    drilling wells in East Java, Indonesia. There are 60 observations that be divided to two
    parts, i.e. the first 50 observations for training data and the last 10 observations for
    testing data. The results show that FFNN-GSTAR(11) and FFNN-VAR(1) as nonlinear
    spatio-temporal models tend to give more accurate forecast than VAR(1) and GSTAR(11)
    as linear spatio-temporal models. Moreover, further research about nonlinear spatiotemporal
    models based on neural networks and GSTAR is needed for developing new
    hybrid models that could improve the forecast accuracy.
  10. Siti Rohani Mohd Nor, Fadhilah Yusof, Arifah Bahar
    MATEMATIKA, 2018;34(2):227-233.
    MyJurnal
    The incorporation of non-linear pattern of early ages has led to new research
    directions on improving the existing stochastic mortalitymodel structure. Several authors
    have outlined the importance of encompassing the full age range in dealing with longevity
    risk exposure, by not ignoring the dependence between young and old ages. In this study,
    we consider the two extensions of the Cairns, Blake and Dowd model that incorporate the
    irregularity profile seen at the mortality of lower ages, which are the Plat, and the O’Hare
    and Li models respectively. The models’ performances in terms of in-sample fitting and
    out-sample forecasts were examined and compared. The results indicated that the O’Hare
    and Li model performs better as compared to the Plat model.
  11. Siti Nur Haseela Izani, Anati Ali
    MATEMATIKA, 2019;35(2):187-200.
    MyJurnal
    The heat and mass transfer of steady magnetohydrodynamics of dusty Jeffrey fluid past an exponentially stretching sheet in the presence of thermal radiation have been investigated. The main purpose of this study is to conduct a detailed analysis of flow behaviour of suspended dust particles in non-Newtonian fluid. The governing equations hav been converted into dimensionless form, and then solved numerically via the Keller-box method. The expression of Sherwood number, Nusselt number and skin friction have been evaluated, and then displayed in tabular forms. Velocity, temperature and concentration profiles are presented graphically. It is observed that large value of dust particles mass concentration parameter has reduced the flow velocity significantly. Increase in radiation parameter enhances the temperature, whereas the increment in Schmidt number parameter reduces the concentration.
  12. Siti Nor Asiah binti Isa, Nor’aini Aris, Shazirawati Mohd Puzi, Hoe,Yeak Su
    MATEMATIKA, 2018;34(101):25-32.
    MyJurnal
    This paper revisits the comrade matrix approach in finding the greatest com-
    mon divisor (GCD) of two orthogonal polynomials. The present work investigates on the
    applications of the QR decomposition with iterative refinement (QRIR) to solve certain
    systems of linear equations which is generated from the comrade matrix. Besides iterative
    refinement, an alternative approach of improving the conditioning behavior of the coeffi-
    cient matrix by normalizing its columns is also considered. As expected the results reveal
    that QRIR is able to improve the solutions given by QR decomposition while the nor-
    malization of the matrix entries do improves the conditioning behavior of the coefficient
    matrix leading to a good approximate solutions of the GCD.
  13. Siti Nabilah Syuhada Abdullah, Ani Shabri, Ruhaidah Samsudin
    MATEMATIKA, 2019;35(301):53-64.
    MyJurnal
    Since rice is a staple food in Malaysia, its price fluctuations pose risks to the producers, suppliers and consumers. Hence, an accurate prediction of paddy price is essential to aid the planning and decision-making in related organizations. The artificial neural network (ANN) has been widely used as a promising method for time series forecasting. In this paper, the effectiveness of integrating empirical mode decomposition (EMD) into an ANN model to forecast paddy price is investigated. The hybrid method is applied on a series of monthly paddy prices from February 1999 up to May 2018 as recorded in the Malaysian Ringgit (MYR) per metric tons. The performance of the simple ANN model and the EMD-ANN model was measured and compared based on their root mean squared Error (RMSE), mean absolute error (MAE) and mean percentage error (MPE). This study finds that the integration of EMD into the neural network model improves the forecasting capabilities. The use of EMD in the ANN model made the forecast errors reduced significantly, and the RMSE was reduced by 0.012, MAE by 0.0002 and MPE by 0.0448.
  14. Siti Mariam Norrulashikin, Fadhilah Yusof, Kane, Ibrahim Lawal
    MATEMATIKA, 2018;34(1):73-85.
    MyJurnal
    Simulation is used to measure the robustness and the efficiency of the forecasting
    techniques performance over complex systems. A method for simulating multivariate
    time series was presented in this study using vector autoregressive base-process. By
    applying the methodology to the multivariable meteorological time series, a simulation
    study was carried out to check for the model performance. MAPE and MAE performance
    measurements were used and the results show that the proposed method that consider
    persistency in volatility gives better performance and the accuracy error is six time smaller
    than the normal hybrid model.
  15. Shazmeen Daniar Shamsuddin, Nurlyana Omar, Koh, Meng-Hock
    MATEMATIKA, 2017;33(2):149-157.
    MyJurnal
    It has come to attention that Malaysia have been aiming to build its own
    nuclear power plant (NPP) for electricity generation in 2030 to diversify the national
    energy supply and resources. As part of the regulation to build a NPP, environmental
    risk assessment analysis which includes the atmospheric dispersion assessment has to
    be performed as required by the Malaysian Atomic Energy Licensing Board (AELB)
    prior to the commissioning process. The assessment is to investigate the dispersion of
    radioactive effluent from the NPP in the event of nuclear accident. This article will focus
    on current development of locally developed atmospheric dispersion modeling code
    based on Gaussian Plume model. The code is written in Fortran computer language
    and has been benchmarked to a readily available HotSpot software. The radionuclide
    release rate entering the Gaussian equation is approximated to the value found in the
    Fukushima NPP accident in 2011. Meteorological data of Mersing District, Johor of
    year 2013 is utilized for the calculations. The results show that the dispersion of radionuclide
    effluent can potentially affect areas around Johor Bahru district, Singapore
    and some parts of Riau when the wind direction blows from the North-northeast direction.
    The results from our code was found to be in good agreement with the one
    obtained from HotSpot, with less than 1% discrepancy between the two.
  16. Shaymaa Mustafa, Zainal Abdul Aziz, Arifah Bahar, Mohd Khairul Nizar Shamsuddin
    MATEMATIKA, 2018;34(2):261-269.
    MyJurnal
    Riverbank filtration (RBF) system is a surface water technology that is based
    on the natural treatment of filtration instead of the use of chemicals, to pre-treat sur-
    face water and provides public water supplies. Hydraulic conductivity value is one of the
    significant factors affecting the water quality in RBF systems. In this article, an analyti-
    cal modelling is developed to investigate the effect of this parameter on one dimensional
    contaminant transport in RBF system. The model is solved by using Green’s function
    approach. The model is applied for the first RBF system conducted in Malaysia. Gener-
    ally, the results show that increasing the hydraulic conductivity value lead to an increase
    in contaminant concentration in pumping well area.
  17. Sagir, Abdu Masanawa, Sathasivam, Saratha
    MATEMATIKA, 2017;33(1):1-10.
    MyJurnal
    In the recent economic crises, one of the precise uniqueness that all stock
    markets have in common is the uncertainty. An attempt was made to forecast future
    index of the Malaysia Stock Exchange Market using artificial neural network (ANN)
    model and a traditional forecasting tool – Multiple Linear Regressions (MLR). This
    paper starts with a brief introduction of stock exchange of Malaysia, an overview of
    artificial neural network and machine learning models used for prediction. System
    design and data normalization using MINITAB software were described. Training
    algorithm, MLR Model and network parameter models were presented. Best training
    graphs showing the training, validation, test and all regression values were analyzed.
  18. S. Alrehaili, C. Beddani
    MATEMATIKA, 2019;35(2):271-282.
    MyJurnal
    The commutativity degree is the probability that a pair of elements chosen randomly from a group commute. The concept of commutativity degree has been widely discussed by several authors in many directions. One of the important generalizations of commutativity degree is the probability that a random element from a finite group G fixes a random element from a non-empty set S that we call the action degree of groups. In this research, the concept of action degree is further studied where some inequalities and bounds on the action degree of finite groups are determined. Moreover, a general relation between the action degree of a finite group G and a subgroup H is provided. Next, the action degree for the direct product of two finite groups is determined. Previously, the action degree was only de?ned for ?nite groups, the action degree for ?nitely generated groups will be de?ned in this research and some bounds on them are going to be determined.
  19. Rose Irnawaty Ibrahim, Norazmir Mohd Nordin
    MATEMATIKA, 2020;36(3):209-216.
    MyJurnal
    Aging is a good indicator in demographic and health areas as the lifespan
    of the elderly population increases. Based on the government’s Economic Outlook 2019,
    it was found that an aging population would increase the government pension payments
    as the pensioners and their beneficiaries have longer life expectancy. Due to mortality
    rates decreasing over time, the life expectancy tends to increase in the future. The
    aims of this study are to forecast the mortality rates in the years 2020 and 2025 using
    the Heligman-Pollard model and then analyse the effect of mortality improvement on
    the pension cost (annuity factor) for the Malaysian population. However, this study
    only focuses on estimating the annuity factor using life annuities through the forecasted
    mortality rates. The findings indicated that the pension cost is expected to increase if
    the life expectancy of the Malaysian population increases due to the aging population
    the near future. Thus, to reduce pension costs and help the pensioners from insufficient
    financial income, the government needs to consider an extension of the retirement age in
    future.
  20. Pandiya, Ridwan, Ismail Mohd
    MATEMATIKA, 2017;33(1):43-54.
    MyJurnal
    In this paper, we propose a method how to manage the convergence of
    Newton’s method if its iteration process encounters a local extremum. This idea establishes
    the osculating circle at a local extremum. It then uses the radius of the
    osculating circle also known as the radius of curvature as an additional number of
    the local extremum. It then takes that additional number and combines it with the
    local extremum. This is then used as an initial guess in finding a root near to that
    local extremum. This paper will provide several examples which demonstrate that the
    proposed idea is successful and they perform to fulfill the aim of this paper.
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