Showing papers by "Universiti Teknologi Malaysia published in 2004"

Targeting the minimum water flow rate using water cascade analysis technique

Abstract: This work presents the water cascade analysis (WCA) as a new technique to establish the minimum water and wastewater targets for continuous water-using processes. The WCA is a numerical alternative to the graphical water targeting technique known as the water surplus diagram. The WCA is to the water surplus diagram in water pinch analysis (WPA) as problem table analysis (PTA) is to the grand composite curves in heat pinch analysis. By eliminating the tedious iterative steps of the water surplus diagram, the WCA can quickly yield accurate minimum water targets, pinch point locations, and water allocation targets for a maximum water recovery (MWR) network, thereby offering a key complementary role to the water surplus diagram in the synthesis of water network. As in the case of the water surplus diagram, the WCA is not limited to mass-transfer–based operations and is applicable to a wide range of water-using operations.

Stagnation point flow of a micropolar fluid towards a stretching sheet

Abstract: The steady two-dimensional stagnation point flow of an incompressible micropolar fluid over a stretching sheet when the sheet is stretched in its own plane with a velocity proportional to the distance from the stagnation point, has been studied in this paper. The resulting equations of non-linear ordinary coupled differential equations are solved numerically using the Keller–box method. The results obtained for velocity, microrotation and skin friction are shown in tables and graphs. Comparison with the recent results of Mahapatra and Gupta {Heat Mass Transfer 38 (2002) 517} for the corresponding problem of a viscous fluid ( K =0) has been done and it has been shown that the results are in excellent agreement.

Arsenic removal technologies for drinking water treatment

Abstract: Arsenic contamination as a consequence of human activities such as mining and pesticide use is affecting the water resource quality worldwide. Because of the high risk of arsenic exposure, specific water treatment processes are required to meet the anticipated more severe water quality standards. Better understanding of presently available processes is necessary to develop economic, efficient and effective methods for arsenic removal. Arsenic could either be coagulated, adsorbed using a wide range of materials both mineral and organic or could be directly rejected by membrane processes such as reverse osmosis and nanofiltration. The recent development of submerged hybrid membrane systems, such as membrane bioreactor in wastewater treatment, offers alternative technologies for arsenic treatment. The membrane in hybrid systems allows a better phase separation between the particles binding the arsenic and the treated water. The effect of pH and contact time, and the existence of other ionic compounds must be taken into account when designing the system for optimum arsenic rejection. Further research on both hydraulic and removal performances of hybrid adsorption/membrane technology is still required to assess the full potential of this technology for arsenic removal.

Cement-based solidification for the safe disposal of blasted copper slag

Abstract: This paper describes an investigation of cement-based solidification/stabilization process for the safe disposal of blasted copper slag. The treatments evaluated were based on ordinary Portland cement (OPC). Mortar specimens with ground copper slag ranging from 0% to 10% by weight of cement were tested for whole block and crushed block leachability, compressive strength and hydration. The results indicated that the leaching of selected heavy metal ions from the cement matrix was low and did not exceed the Malaysian Environmental Quality Act. Addition of copper slag to cement increased initial and final setting times. The primary hydration process was the OPC hydration. The strength of the copper slag mortar was generally lower than that of the control mortar and the amount of ground copper slag to replace cement for optimum strength was about 5%.

Immobilised lipase-catalysed resolution of (R,S)-1-phenylethanol in recirculated packed bed reactor

Abstract: Six commercial immobilised lipases were screened for the resolution of (R,S) -1-phenylethanol in organic solvent. Among them, lipases from Pseudomonas cepacia (ChiroCLEC-PC) and Candida antarctica lipase B (Chirazyme L2, c.-f., C3, lyo) were used in the kinetic study of the resolution in batch stirred tank reactor (BSTR). Lauric acid was used as acyl donor in the acyl transfer reaction. This enzymatic resolution was carried out at 35 °C in isooctane. The enzyme activity as well as enantioselectivity was determined by varying substrates concentration from 25 to 250 mM, acyl length of fatty acid from C12 to C18, organic solvents with log P values from 1.4 to 4.5 and reaction temperature from 25 to 50 °C. An initial reaction velocity approach was used to determine the enzymes activities and a computer software, SELECTIVITY was used to calculate the enzyme enantioselectivity. The activity of ChiroCLEC-PC and Chirazyme L2, c.-f., C3, lyo are 1.4 kU/g and 1.0 U/g, respectively. The enzymes are highly selective toward the ( R )-enantiomer of the chiral alcohol with the enantiomeric ratio, E >200. A series of reaction progress curves was used to develop a kinetic model based on the principle of mass action law with steady-state assumption. The reaction follows a Ping–Pong Bi–Bi mechanism with substrate inhibition. The performance of Chirazyme L2, c.-f., C3, lyo in the resolution was also investigated in a recirculated packed bed reactor (RPBR). The enzyme performance in term of initial reaction rate was decreased 19% and the volumetric productivity was decreased 7% after 30 min of reaction time. The resolution was also required 350 min longer reaction time in order to achieve equilibrium. A comparable result could be obtained in a five-fold scaling up RPBR.

The use of bivalves as bio-indicators in the assessment of marine pollution along a coastal area

Abstract: The assessment of environmental pollution of the coastal areas of the Malaysian Peninsula was done by analyzing the contents of the heavy and trace elements in the bivalves blood clams (Anadara granosa) and green mussels (Perna viridis) and sediments at twenty-two sampling stations to look for prevailing trends. Heavy and trace elements analyzed in this study were As, Cd, Cr, Cu, Pb, Se and Zn. Two techniques, namely the neutron activation analysis (NAA) and atomic absorption spectrophotometry (AAS) were used in the quantitative determination of the heavy metals while Marine Sediment Reference Material (BCSS) and Lobster Hepatopancreas (TORT-1) provided the certified reference materials in the quality assurance control. The potential use of these bivalves as suitable bio-indicators was evaluated from correlation tests based on the concentrations of heavy and trace elements in the sediment-metals system to those in the bivalves.

Static and dynamic under-frequency load shedding: a comparison

Abstract: Safe operation of a power system requires that system frequency is kept within a specified range. When the generation is insufficient due to disturbances, the frequency might fall under the minimum allowable value which may lead to system blackout if not properly counteracted. This frequency decline may be corrected by shedding certain amount of load so that the system is back into balanced state. In this paper several under-frequency load shedding schemes are reviewed. Comparison are made between static scheme which shed a fixed, predetermined amount of load at each stage and a dynamic system which shed the load by taking into account the size of the disturbance and the voltage and frequency characteristics. Simulations were done on a five buses power system to obtain the amount of load shed, minimum under-frequency, number of stages and completion time. Results from the dynamic scheme appear to give a better frequency recovery.

Lime stabilized malaysian cohesive soils

Abstract: This paper highlights the essential tests for assessing the suitability of lime for stabilizing soils and typical changes in soil characteristics due to modification and stabilization processes with respect to mineralogical influences. The reasoning behind the mechanism of lime clay reaction on the compressive strength development of stabilized soils has been established. Clay with acidic origin exhibit less significant increase in compressive strength compared to clay with high intensity of kaolinite and with alkaline origin. In general, lime contents instituted, ranging from 3% to 6%, have contributed to a significant increase in unconfined compressive strength, from 2.5 to 11 times of the untreated soils. The formation of calcium aluminates silicate hydrate (CASH) observed from XRD test, after 14 days, indicates the early formation of new product, due to lime-soil reaction. The effectiveness of stabilization process has been found to be dependent on the quality of the lime, clay fraction, mineralogy and the alkalinity of the soil.

Online handwriting recognition using support vector machine

Abstract: Discrete hidden Markov model (HMM) and hybrid of neural network (NN) and HMM are popular methods in handwritten word recognition system. The hybrid system gives better recognition result due to better discrimination capability of the NN [Y. Bengio et al., 1995]. Support vector machine (SVM) is an alternative to NN. In speech recognition (SR), SVM has been successfully used in the context of a hybrid SVM/HMM system. It gives a better recognition result compared to the system based on hybrid NN/HMM [A. Ganapathiraju, January 2002]. This paper describes the work in developing a hybrid SVM/HMM OHR system. Some preliminary experimental results of using SVM with RBF kernel on IRONOFF, UNIPEN and IRONOFF- UNIPEN character database are provided.

English in Malaysia.

Abstract: This article seeks to lay out the use and importance of English in Malaysia from the time when the British ruled what was then Malaya to the present moment. When the British came to colonize the country, they brought with them their culture, their language and their beliefs. They introduced the English language as the medium of instruction in the primary and secondary schools. After Independence, nationalistic sentiments arose and in 1970, Bahasa Malaysia was introduced as the medium of instruction in the schools. With the advancement in science and technology and the advent of globalization, English regained part of its lost status. It is now taught in the schools both at the primary and secondary school level and it is also used to teach Science and Mathematics. Besides, it is the medium of instruction in the private colleges. Currently, the mastery of the English language is much encouraged at all levels of education—from the primary to the tertiary level. Moreover, English is much needed in the commer...

GPS-free indoor location tracking in mobile ad hoc network (MANET) using RSSI

Abstract: More devices in the future will be connected to the Internet wirelessly and also these devices can move within the coverage area of the mobile network. A mobile ad hoc network consists of devices or nodes that are able to communicate among themselves. These nodes also serve as routers and can dynamically move around arbitrarily at any speed in any direction resulting in an ever-changing topology for the MANET. Due to the node mobility, the most challenging issue is to design a routing protocol that guarantees delivery of packets. In order to improve the network routing performance, a limited casting technique is adopted which requires the ability to establish position information. Once each node's location is determined, the distance between nodes can be derived and the number of hops to the destination can be computed. A GPS-free indoor position tracking system has been developed that provides knowledge of the geometric location of nodes in a MANET.

Developing Generic Skills in Classroom Environment: Engineering Students’ Perspective

Abstract: The two greatest concerns of employers today are finding good workers and training them. The difference between the skills needed on the job and those possessed by applicants, sometimes called the skills-gap, is of real concern to human resource managers and business owners looking to hire competent employees. While employers would prefer to hire people who are trained and ready to go to work, they are usually willing to provide the specialized, jobspecific training necessary for those lacking such skills. Most discussions concerning today’s workforce eventually turn to employability or generic skills. Finding workers who have generic or job readiness skills that help them fit into and remain in the work environment is a real problem. Universiti Teknologi Malaysia has launched its list of graduate attributes in the second quarter of 2004 in which the university believes will enable its graduates to function effectively in a wide range of social and professional contexts. A class of fourty final year undergraduate chemical engineering students were asked to score their competencies on the seven attributes listed by the university and to give suggestions on ways of improving the skills required in the class room environment.

A review on level of detail

Abstract: Advances in modern 3D scanning technology and the increasingly size of computer simulations have led to a rapid increase in the availability and size of geometry data sets. Gigantic polygonal data sets, consisting of hundreds of millions of faces, are becoming quite common. While the performance of graphics hardware also seen a drastic rise in these years, however, ability to produce enormous data sets overload the capabilities of the state-of-the-art graphics chip. Therefore, automatic model simplification and run-time level of detail (LOD) management techniques are introduced. We present a review on level of detail techniques in an organized structure. Level of detail framework, level of detail management, level of detail simplification models and metrics for simplification and error evaluation are discussed in sequence. Finally, some current issues and conclusion are given.

Modelling the propagation of a radar signal through concrete as a low-pass filter

Abstract: The knowledge of how a dispersive, dielectric medium such as concrete affects a propagating short electromagnetic pulse used in ground penetrating radar (GPR) is helpful both in the interpretation of radar results and in the prediction/modelling of expected radar measurements. Although there are a number of published results on the frequency-dependent, dielectric properties of media such as concrete and soils, the use of this information is still relatively small, primarily due the lack of a reliable method of applying these properties to propagating radar pulses. Modelling the dielectric medium as low-pass filter is one solution to this difficulty. In this paper the propagation of short pulses in concrete with known frequency-dependent properties is studied. The extent of how the pulses are attenuated and distorted is analysed and the implications on GPR applications are also discussed.

A novel method for ATC computations in a large-scale power system

Abstract: In a restructured power system, it is the responsibility of the independent system operator (ISO) to control the power transactions and avoid overloading of the transmission lines beyond their thermal loading megavolt-ampere (MVA) limits. For this, ISO has to update periodically a real-time index termed available transfer capability (ATC). The methods reported to date for ATC determination are unable to cater to either the accuracy or the online CPU time requirements when the system is a large one. This paper proposes a novel method with the full details for determining ATC in a large power system from only three input variables through fuzzy modeling. The method is validated through extensive simulation tests on the standard IEEE 24-bus reliability test system (RTS), and comparison with an ac load flow-based conventional method using the same array of transactions, base cases, and generation/line outages.