Soil properties are very crucial for civil engineers to differentiate one type of soil from another and to predict its mechanical behavior. However, it is not practical to measure soil properties at all the locations at a site. In this paper, an estimator is derived to estimate the unknown values for soil properties from locations where soil samples were not collected. The estimator is obtained by combining the concept of the ‘Inverse Distance Method’ into the technique of ‘Kriging’. The method of Lagrange Multipliers is applied in this paper. It is shown that the estimator derived in this paper is an unbiased estimator. The partiality of the estimator with respect to the true value is zero. Hence, the estimated value will be equal to the true value of the soil property. It is also shown that the variance between the estimator and the soil property is minimized. Hence, the distribution of this unbiased estimator with minimum variance spreads the least from the true value. With this characteristic of minimum variance unbiased estimator, a high accuracy estimation of soil property could be obtained.
In this paper, stormwater runoff from a residential catchment located in Miri, Sarawak, was characterized to determine the pollutant concentrations and loading. The observed average event mean concentrations were 116 mg/L for TSS, 115 mg/L for COD, 1.5 mg/L for NH3-N, and 0.23 mg/L for Pb. Based on Interim National Water Quality Standards (INWQS) for Malaysia, the average event mean concentration, EMC value for TSS exceeded class II (50 mg/L), exceeded class V (>100 mg/L) for COD, and exceeded class III (0.9 mg/L) for NH3-N. All four water quality parameters exhibited first flush characteristic but to varying magnitude which was influenced by the storm characteristics.
This paper presents a two-staged, pilot-scale vertical flow engineered wetland-based septage treatment system (VFEWs), which was designed and constructed in Curtin University Sarawak Campus to determine the system efficiency in treatment of septage. The treatment system consists of storage tanks, vertical flow wetlands, and a network of influent and effluent distribution pipes. The first stage of the VFEWs treatment system consists of three vertical flow wetlands placed in parallel to provide pre-treatment to raw septage to reduce solids and organic matters mainly by physical filtration and sedimentation processes. The percolate from the first stage is then further treated in the second stage, with four vertical flow wetlands, each with variation in operational regime and substrate (filter) type. The influences of various system and application-related parameters such as substrate material, presence of plants and plant types, and septage feeding practices (solid loading rate (SLR), batch and intermittent loading, and frequency of daily feeding) on pollutant removal efficiency were studied. Results from the first stage wetlands indicate that the removal of total solids and organic matter (BOD and COD) from the raw septage is promising (> 80%) at both SLR of 100 kg TS/m2 .yr and 250 kg TS/m2 .yr, respectively. However, a higher SLR decreased the average NH3-N removal efficiency. The findings on bed clogging assessment during the study period are also presented in this paper. Validation and expansion of these results are carried out with ongoing assessments on the system performance.
Autocorrelation problem causes unduly effects on the variance of Ordinary Least Squares (OLS) estimates. Hence, it is very essential to detect the autocorrelation problem so that appropriate remedial measures can be taken. The Breusch-Godfrey (BG) test is the most popular and commonly used test for the detection of autocorrelation. Since this test is based on the OLS estimates, which are not robust, it is easily affected by outliers. In this paper, we propose a robust Breusch-Godfrey (MBG) test which is not easily affected by outliers. The results of the study indicate that the MBG test is more powerful than the BG test in the detection of autocorrelation problem.
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.
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.
This paper presents the numerical modelling techniques for the simulation of the energy conversion chain from wave to electricity in an Oscillating Water Column (OWC) equipped with a full-scaled self rectifying turbine. The performance of the OWC device has been assessed for the stand-alone power system of a typical Irish climatic wave condition. The results showed that the overall performance of the complete device depends on the level of turbine damping, which in turn depends on the wave climate, especially the significant wave height. Furthermore, turbine efficiency predicted using quasi-steady showed qualitatively favourable agreement with the experimental results.
In this paper we present a new line search method known as the HBFGS method, which uses the search direction of the conjugate gradient method with the quasi-Newton updates. The Broyden-Fletcher-Goldfarb-Shanno (BFGS) update is used as approximation of the Hessian for the methods. The new algorithm is compared with the BFGS method in terms of iteration counts and CPU-time. Our numerical analysis provides strong evidence that the proposed HBFGS method is more efficient than the ordinary BFGS method. Besides, we also prove that the new algorithm is globally convergent.
The paper reconsiders the problem of the mixed convection boundary layer flow near the lower stagnation point of a horizontal circular cylinder with a second order slip velocity model and a constant surface heat flux studied recently by RoKa et al. (2013). The ordinary (similarity) differential equations are solved numerically using the function bvp4c from Matlab for different values of the governing parameters. It is found that the similarity equations have two branches, upper and lower branch solutions, in a certain range of the mixed convection parameters. A stability analysis has been performed to show that the upper branch solutions are stable and physically realizable, while the lower branch solutions are not stable and therefore, not physically possible. This stability analysis is different by that presented by RoKa et al. (2013), who have presented a time-dependent analysis to determine the stability of the solution branches.
A quadratic stochastic operator (Qso) is usually used to present the time evolution of differing species in biology. Some quadratic stochastic operators have been studied by Lotka and Volterra. The general problem in the nonlinear operator theory is to study the behavior of operators. This problem was not fully finished even for quadratic stochastic operators which are the simplest nonlinear operators. To study this problem, several classes of QSO were investigated. In this paper, we study the fri)-Qso defined on 2D simplex. We first classify 4-(a)-QS0 into 2 non-conjugate classes. Further, we investigate the dynamics of these classes of such operators.
This paper is focussed on conductivity and dielectric properties of Poly (vinyl) chloride (Pvc)- ammonium triflate (NH4CF3SO3) - butyltrimethyl ammonium bis (trifluoromethyl sulfonyl) imide (Bu3MeNTf2N) ionic liquid, electrolyte system. The electrolyte is prepared by solution cast technique. In this work, the sample containing 30 wt. % NH4CF3SO3 exhibits the highest room temperature conductivity of 2.50 x 10-7 S cm' . Ionic liquid is added in various quantities to the 70 wt. % Pvc-30 wt. % NH4CF3SO3 composition in order to enhance the conductivity of the sample. The highest conductivity at room temperature is obtained for the sample containing 15 wt. % Bu3MeNTf2N with a value of 1.56 x 10 -4 S cm' . The effects of ionic liquid addition on the frequency dependent dielectric properties of PVC based electrolytes is investigated by electrochemical impedance spectroscopy (Eis) at room temperature. The values of dielectric constant were found to increase with increasing conductivity of the samples. Analysis of the ac conductivity data showed the electrolytes to be of the non-Debye type.
Missing values have always been a problem in analysis. Most exclude the missing values from the analyses which may lead to biased parameter estimates. Some imputations methods are considered in this paper in which simulation study is conducted to compare three methods of imputation namely mean substitution, hot deck and expectation maximization (EM) imputation. The EM imputation is found to be superior especially when the percentage of missing values is high as it constantly gives low RMSE as compared with other two methods. The EM imputation method is then applied to the PM10 concentrations data set for the southwest and northeast monsoons in Petaling Jaya and Seberang Perai, Malaysia which has missing values. Four types of distributions, namely the Weibull, lognormal, gamma and Gumbel distribution are considered to describe the PM10 concentrations. The Weibull distribution gives the best fit for the southwest monsoon data for Petaling Jaya. The lognormal distribution outperformed the others in describing the southwest monsoon in Seberang Perai. Meanwhile, for the northeast monsoon in both locations, gamma distribution is the best distribution to describe the data.
Quality of bond between layers of asphaltic concrete course is a key element to ensure the performance of a modern asphalt pavement. A proper interlayer bond ensures the structural integrity of the pavement and prevents possible distresses from occurring within the designed service life. In Malaysia, delamination is a common distress related to insufficient degree of adhesion though slippage failure can be occasionally encountered. Generally, bond development is closely related to the design factors and construction factors. This paper however focused on the construction factors only, hoping to provide some useful information which might be overlooked by the contractors during construction but is of extreme important especially in enhancing the bond development in the asphalt layers. The construction factors in particular interest discussed in this paper include curing time of asphalt emulsion, surface condition of a pavement and technology and quality of workmanship and construction. It is important to note that both design factors and construction factors are inter-related in optimizing the degree of adhesion. Thus, all factors need to be carefully identified and fulfilled in order to maximize the bond strength between pavement surfacing layers for a better quality and longer service life of pavement in Malaysia.
The paper is aimed at studying fluid flow heat transfer in the axisymmetric boundary layer flow of a viscous incompressible fluid, along the axial direction of a vertical stationary isothermal cylinder in presence of uniform free stream with momentum slip. The equations governing the flow i.e. continuity, momentum and energy equation are transformed into non-similar boundary layer equations and are solved numerically employing asymptotic series method with Shanks transformation. The numerical scheme involves the Runge-Kutta fourth order scheme along with the shooting technique. The flow is analyzed for both assisting and opposing buoyancy and the effect of different parameters on fluid velocity, temperature distribution, heat transfer and shear stress parameters is presented graphically.
In this paper, we present a new method for solving nonlinear general two point boundary value problems. A method based on finite differences and rational function approximation and we call this method as rational approximation method. A rational approximation method is applied to construct the numerical solution for two point boundary value problems. The novel method is tested on three model problems. Thus the numerical results obtained for these model problems show the performance and efficiency of the developed method.
In this work, the Sandvik uncoated carbide insert, CNGG 120408-SGF-H13A was used as a cutting tool in high-speed turning of titanium alloy Ti-6A1-4V EH (extra-low interstitial) with hardness of 32 HRC. Wear is one of the problems that cannot be avoided in machining process. Therefore, the objective of this paper was to investigate tool-wear behavior of various cutting-speed values (high-speed range) on the tool life of the cutting tools, especially in finishing titanium alloy. The experiments were performed under flooded coolant condition using water-based mineral-oil. The cutting speeds employed were 120, 170 and 220 mlmin. The feed rate was constant at 02 mm/rev and the depth of cut was 0.4 mm. Based on the results, the highest cutting speed of 220 m/min caused the highest wear rate. By linking the machine operations and the tool life curves obtained using flank wear data, the wear behavior of uncoated carbide was described.
The requirement for high quality pulps which are widely used in paper industries has increased the demand for pulp refining (beating) process. Pulp refining is a promising approach to improve the pulp quality by changing the fiber characteristics. The diversity of research on the effect of refining on fiber properties which is due to the different pulp sources, pulp consistency and refining equipment has interested us to provide a review on the studies over the last decade. In this article, the influence of pulp refining on structural properties i.e., fibrillations, fine formation, fiber length, fiber curl, crystallinity and distribution of surface chemical compositions is reviewed. The effect of pulp refining on electrokinetic properties of fiber e.g., surface and total charges of pulps is discussed. In addition, an overview of different refining theories, refiners as well as some tests for assessing the pulp refining is presented.
The study reports on the preparation of cellulose nanocrystals (CNCs) from wastepaper, as an environmental friendly approach of source material, which can be a high availability and low-cost precursor for cellulose nanomaterial processing. Alkali and bleaching treatments were employed for the extraction of cellulose particles followed by controlled-conditions of acid hydrolysis for the isolation of CNCs. Attenuated total reflectance Fourier Transform Infrared (ATR FTIR) spectroscopy was used to analyze the cellulose particles extracted while Transmission electron microscopy images confirmed the presence of CNCs. The diameters of CNCs are in the range of 3-10nm with a length of 100-300nm while a crystallinity index of 75.9% was determined from X-ray diffraction analysis. The synthesis of this high aspect ratio of CNCs paves the way toward alternative reuse of wastepaper in the production of CNCs.
Electrospun polyhydroxybutyrate (PHB) fibers were dip-coated by polymethyl methacrylate-co-methacrylic acid, poly(MMA-co-MAA), which was synthesized in different molar ratios of the monomers via free-radical polymerization. Fabricated platfrom was employed for immobilization of the dengue antibody and subsequent detection of dengue enveloped virus in enzyme-linked immunosorbent assay (ELISA). There is a major advantage for combination of electrospun fibers and copolymers. Fiber structre of electrospun PHB provides large specific surface area available for biomolecular interaction. In addition, polymer coated parts of the platform inherited the premanent presence of surface carboxyl (-COOH) groups from MAA segments of the copolymer which can be effectively used for covalent and physical protein immobilization. By tuning the concentration of MAA monomers in polymerization reaction the concentration of surface -COOH groups can be carefully controlled. Therefore two different techniques have been used for immobilization of the dengue antibody aimed for dengue detection: physical attachment of dengue antibodies to the surface and covalent immobilization of antibodies through carbodiimide chemistry. In that perspective, several different characterization techniques were employed to investigate the new polymeric fiber platform such as scanning electron microscopy (SEM), atomic force microscopy (AFM), water contact angle (WCA) measurement and UV-vis titration. Regardless of the immobilization techniques, substantially higher signal intensity was recorded from developed platform in comparison to the conventional ELISA assay.
The disposal of industrial paper mill sludge waste is a big issue and has a great importance all over the world. A study was conducted to determine the chemical properties of recycled paper mill sludge (RPMS) and assess its possibilities for land application. RPMS samples were collected from six different paper mills in Malaysia and analyzed for physical and chemical properties, heavy metals, polycyclic aromatic hydrocarbons, (13)C-NMR spectra and for the presence of dioxins/furans. The RPMS was dewatered, sticky with a strong odour, an average moisture of 65.08%, pH 7.09, cation exchange capacity (CEC) 14.43 cmol (+) kg(-1), N 1.45, P 0.18, K 0.12, Ca 0.82, Mg 0.73, Na 0.76 and Al, 1.38%. The polycyclic aromatic hydrocarbons (PAHs) and heavy metals levels were below the standard Class 2 limits. The dioxin and furan were in below the standard concentration of Class 1. The most prominent peak in the (13)C-NMR spectra of RPMS was centered at 31 ppm, proving the presence of methylene (-CH2) groups in long aliphatic chains, with lipids and proteins. The signal at 89 ppm and highly shielded shoulder at 83 ppm were due to presence of cellulose carbon C-4, and the peak at 63 and 65 ppm was due to the cellulose carbon spectrum. The RPMS therefore contains significant amount of nutrients with safe levels of heavy metals and PAHs for environment and can be used as a fertilizer and soil amendment for land application.