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.
This studies are directed towards measuring the electrical conductivity of the (CuSe)1-xSex metal chalcogenide semi-conductor composites, with different stoichiometric compositions of Se (x = 0, 0.2, 0.4, 0.5, 0.6, 0.8,1.0) in bulk form. The electrical conductivity measurement was carried out at room temperature, using the parallel plate technique. The (CuSe)1-xSex composites were prepared using solid state reaction, by varying the ratio of CuSe:Se, in the reaction mixture. The electrical conductivity of (CuSe)1-xSex was determined to be in the range of 1.17 x 10-8 to 1.02 x 10-1 S/cm. The finding indicated that the electrical conductivity value tended to decrease as the concentration of Se increased. The effect of the concentration of Se, on electrical conductivity of (CuSe)1-xSex composites, is discussed in this paper.
This paper is concerned with the existence, types and the cardinality of the integral solutions for
diophantine equation
4 4 3
x y z + = where x , y and z are integers. The aim of this paper was to
develop methods to be used in finding all solutions to this equation. Results of the study show the
existence of infinitely many solutions to this type of diophantine equation in the ring of integers
for both cases, x y = and x y ¹ . For the case when x y = , the form of solutions is given by
3 3 4
( , , ) (4 , 4 ,8 ) x y z n n n = , while for the case when x y ¹ , the form of solutions is given by
3 1 3 1 4 1
( , , ) ( , , )
k k k
x y z un vn n
- - -
= . The main result obtained is a formulation of a generalized method to find
all the solutions for both types of diophantine equations.
Mobile users have the capability of accessing information anywhere at any time with the introduction of mobile browsers and mobile web search. However, the current mobile browsers are implemented without considering the characteristics of mobile searches. As a result, mobile users need to devote time and effort in order to retrieve relevant information from the web in mobile devices. On the other hand, mobile users often request information related to their surroundings, which is also known as context. This recognizes the importance of including context in information retrieval. Besides, the availability of the embedded sensors in mobile devices has supported the recognition of context. In this study, the context acquisition and utilization for mobile information retrieval are proposed. The “just-in-time” approach is exploited in which the information that is relevant to a user is retrieved without the user requesting it. This will reduce the mobile user’s effort, time and interaction when retrieving information in mobile devices. In this paper, the context dimensions and context model are presented. Simple experiments are shown where user context is predicted using the context model.
A Boolean permutation is called nonlinear if it has at least one nonlinear component function. All nonlinear Boolean permutations and their complements are called non-affine Boolean permutations. Any non-affine Boolean permutation is a potential candidate for bijective S-Box of block ciphers. In this paper, we find the number of n-variable non-affine Boolean permutations up to multiplicative n and show a simple method of construction of non-affine Boolean permutations. However, non-affinity property is not sufficient for S-Boxes. Nonlinearity is one of the basic properties of an S-Box. The nonlinearity of Boolean permutation is a distance between set of all non-constant linear combinations of component functions and set of all non-affine Boolean functions. The cryptographically strong S-Boxes have high nonlinearity. In this paper, we show a method of construction of 8-variable highly nonlinear Boolean permutations. Our construction is based on analytically design (8, 1), (8, 2), and (8, 3) highly nonlinear vectorial balanced functions and random permutation for other component functions.
The finite element method is gaining acceptance in predicting mechanical response of various loading configurations and material orientations for failure analysis of composite laminates. Both fabrication of laminate samples and experimental procedures are often expensive and time consuming, and hence impractical, especially during the initial design stage. Finite element analyses require minimal amounts of input data, and the resulting stress and strain distributions can be determined throughout each individual ply. Using ANSYSTM, a commercially available finite element package, failure loads were predicted by simulating a uniaxial tensile loading on HTS40/977-2 Carbon/Epoxy composite with [+/-4512s lamination scheme. Two built-in failure theories in ANSYSTM features, viz., Maximum Stress and Tsai-Wu were applied in the simulation. The stress-strain and load-extension curves for both actual testing and FEA were then compared and the results are in good agreement. This paper is intended for researchers who have used or are considering using ANSYSTM for the prediction of failure in composite materials.
The advancement in communication and Internet technology leads to mass of online data available on the Internet. People communicate to each other with application such as Facebook, Twitter, Short Message Service and e-forum. Entries or posts from these applications are known as microtexts. Normally a microtext is very short, very noisy and does not follow the correct structure of a sentence either in the English language or the Malay language. High occurrence of noisy texts decreases the accuracy value when microtexts are processed. This paper proposes a prototype of a system known as Sistem Penterjemahan Mesej Atas Talian (SPMAT). The objective of the system is to 'clean' noisy texts in microtexts that are created online by the Malaysian. 5000 Facebook messages, 5000 Twitter messages and 5000 e-forum messages were collected. From these sources, few lists such as common noisy texts list, common acronyms list artificial abbreviations list and Bi-gram index were created and used in the normalization processed. In addition, the system kept messages that it normalized and updated the corpus when instructed by the user. The methods used in SPMAT had been tested with 100 online messages. The result indicated that 80% of the noisy texts incorporated in these messages had been identified and cleaned correctly.
One of the non-destructive methods used for the identification and verification of metals is by the energy-dispersive X-ray fluorescence (EDXRF) technique. EDXRF analysis provides several important advantages such as simultaneous determination of the elements present, enable to analyse a very wide concentration range, fast analysis with no tedious sample preparation. The paper shows how this technique is developed and applied in the identification and verification of different grades of stainless steels. Comparison of the results obtained from this analysis with certified reference standards show very small differences between them.
This paper studies the use of gamma irradiation for textile waste water treatment. Prior to irradiation, the raw wastewa ter was diluted using tap water to targeted concentration of COD 400 mg/l. The sample was irradiated at selected dose between the ranges of 2kGy to 100kGy. The results showed that Irradiation was effective in removing the highly colored refractory organic pollutants. The COD removal at lowest dose, 2kGy is about 310 mg/l. Meanwhile, at highest dose, 1 00kGy the COD reduced to 100mg/l. The degree of removal influenced by the dose introduced during the treatment pro cess. As the dose increased, higher removal of organic pollutant was recorded. On the other hand, other properties of t he wastewater such as pH, turbidity, suspended solid, BOD and color shows tremendous changes as the dose increases. This shows the concentration of pollutants and dose of irradiation applied are directly proportional to each other.
The paper describes the uses of microfocus XRF to identify infected Basal Stem Rot (BSR) disease in Malaysian palm oil plants. Among symptoms of BSR are wilting of the leaves and plant malnutrition. The study involves determining the inorganic element content of normal and infected leaves. Si, Mo, Cl, K, Ca and Mn had been identified as the major elements. Their distribution was determined by constructing an elemental map of each of this element on the leaves. Line scan was also performed to look into changes on the element composition on a defined region. Quantitative analysis of Cl, Ca and K on the normal and infected leaves show that the infected leaves have lower Cl content and a higher Ca/K ratio than the normal leaves.
The paper relates a study on the development of an analysis procedure for measuring the gold coating thickness using EDXRF technique. Gold coating thickness was measured by relating the counts under the Au Lα peak its thickness value. In order to get a reasonably accurate result, a calibration graph was plotted using five gold-coated reference standards of different thicknesses. The calibration graph shows a straight line for thin coating measurement until 0.9μm. Beyond this the relationship was not linear and this may be resulted from the selfabsorption effect. Quantitative analysis was also performed on two different samples of goldcoated jewelry and a phone connector. Result from the phone connector analysis seems to agree with the manufacturer’s gold coating value. From the analysis of gold-coated jewelry it had been able to differentiate the two articles as gold wash and gold electroplated.
Batu Reput’ is primary sediment mineral and abundantly found in Perlis. Perlis is one of the major producers of ‘Batu Reput’ in Malaysia that content large deposit of high-purity dolomite [CaMg (CO3)2]. Pure samples of ‘Batu Reput’ recently explored in the Koperasi Rimba Mas Padang Besar Quarry were investigated for their physical, chemical and mineralogical composition. SEM and XRD analysis methods were applied. The potential of ‘Batu Reput’ as a raw material in fertilizer production was investigated in this paper.
Recently, there has been great interest on the applicability of Recycled Concrete Aggregate (RCA) as a new ecological construction material that can be sustainable in a gradually expanding construction industry. This paper reports the structural performance particularly on shear behaviour of high strength reinforced recycled concrete beams. Compressive cube strength of the tested beams ranged from 65-74 MPa at the age of 28-days. The experimental program compared conventional concrete mix with concrete mix having substitution of 25% recycled concrete aggregates of grade 25-30 MPa. In this study, three 150 mm x 200 mm x 1200 mm simply supported rectangular concrete beams in each mix were tested under a four-point bending static load with various shear span to effective depth ratios (a/d = 1.0, 1.5, 2.0). Subsequently, the shear behavior of the beams was investigated through studies of load-deflection responses, effect of a/d ratios and crack patterns. The test results reported that the substitution of 25% recycled concrete coarse aggregates barely affects the shear capacity of the high strength reinforced concrete beams with a/d of 1.5 onwards. Finally, experimental results were compared using existing design codes by ACI 318, Eurocode-2 and AS3600 which lie on the safe side.
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.
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.
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.
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.
This paper presents an evaluation of the alternative use of natural cellulose coir fibres for
soil reinforcement. Soil reinforcement is defined as a technique to improve the engineering properties
of soil. Inserting natural fibres into the soil has been proposed as a reinforcement method. Randomly
distributed coir fibre reinforced soils have recently attracted increasing attention in geotechnical
engineering due to their strength. Furthermore, there is a need to develop an innovative and
sustainable pre-treatment method to improve the effectiveness and performance of coir fibre as soil
reinforcement. The primary purpose of this paper is, therefore, to review the characteristics, benefits,
applications and weaknesses of coir fibre as soil reinforcement.
This paper presents the housing improvement proposition in the Melaka resident area.Quality Function Deployment is used as a method to analyze customer behavior regarding customer requirement, satisfaction and comparison among the developers. By using this method, the main requirement by the buyer for their bungalow is their need of sufficient space to place their appliances in the house. At the end of the study, the details of buyer requirements are plotted into House of Quality, where it is believed to improve the quality of future bungalow house development in Melaka.