Showing papers by "Universiti Teknologi Malaysia published in 1994"

A GIS approach to spatial modelling for squatter settlement planning in Kuala Lumpur, Malaysia

Abstract: The most pressing problems of rapid urbanisation in Kuala Lumpur include the need for land, housing, and provision of services. The link with day-to-day planning problems, how ever, remains a critical problem. The quality of the planning and decisionmaking process can be substantially improved when valid data are appropriately and efficiently handled. The aim of this paper is to demonstrate the use of geographic information systems (GISs) in evaluating alternative solutions to squatter problems. After the initial development of the GIS database, it has been used to produce various scenarios which take into account the socioeconomic characteristics of the squatters, the constraints of the physical layout of existing squatter settlements, availability of land, and site suitability of different kinds of development. Spatial modelling techniques are employed to examine alternative plans for the squatter areas. These plans are evaluated by means of cost-benefit analysis incorporated into the GIS database. The authors also discuss the development of an interactive graphic user-interface to the GIS for squatter planning and management. This is intended to facilitate user access to squatter-planning scenarios. The interface provides flexibility in data selection and display, to allow physical planners and decision-makers to view and analyse the planning scenarios interactively before deciding on the final plan. In a concluding section some of the problems encountered are highlighted and factors which need to be considered if GIS is to be employed in this type of exercise are indicated.

The accumulation and distribution of trace metals in some localized marine species.

Abstract: Trace elements, such as As, Co, Cr, Hg, Sb, and Zn, were determined by neutron activation analysis (NAA), whereas Cd, Cu, and Pb were determined by graphite furnace atomic absorption spectroscopy (GFAAS) in clam, crab, prawn, swamp cerith, and mussel samples after digestion by microwave heating under controlled conditions before eluting the solutions through a column of a chelating resin, Chelex-100. The standard used in the determination of percentage volatile elements retained by microwave digestion and also in the activation process was Lobster Hepatopancreas TORT-1, whereas known mixed standards were prepared from nitrate salts to determine the efficiency of the separation procedure at a controlled pH. Mercury and lead detected in crabs exceeded the maximum permissible level. Some species also showed a high affinity toward certain elements, and their levels of accumulation in the tissues of these species corresponded with the concentration of these elements in sediments, especially at sites in the vicinity of an industrial zone.

Essential oil of Zingiber ottensii Valeton

Abstract: The essential oil of the rhizomes of Zingiber ottensii Valeton of Malaysia has been analyzed by a combination of capillary GC and GC/M S. Twenty-six components have been identified of which the major component was found to be zerumbone (25.6%)

Electrical conductivity measurements in evaporated tin sulphide thin films

Abstract: Tin sulphide (SnS) has been evaporated on to substrates maintained at fixed temperatures in the range 50-300°C. X-ray diffraction measurements have shown that the films deposited at the lower substrate temperatures are non-stoichiometric, containing higher sulphides of tin, but that those deposited at 300°C consist essentially only of SnS. Film conductivity increased in the range 0·5-20 Sm-1 as the substrate temperature during deposition increased from 50°C to 250°C, this effect being attributed to the changing film composition. Films deposited at 50°C and 150°C showed thermally activated conductivity at temperatures above 220-250 K, with activation energies EB; of 0·12 eV and 014eV, respectively. At lower temperatures both conductivity and activation energy were considerably lower, consistent with hopping via localized states. The conductivity is modified after prolonged cooling to 160K, although the mechanism of this process is not understood

Adaptive fuzzy-neuro control with application to a water bath process

Abstract: The emergence of artificial neural networks has made it conducive to integrate fuzzy logic controllers and neural models for the development of adaptive fuzzy control systems. In this paper, the authors proposed an adaptive fuzzy-neural control scheme by integrating two neural network models with a basic fuzzy logic controller. Using the backpropagation algorithm the first neural network is trained as a plant emulator and the second neural network is used as a compensator for the basic fuzzy controller to improve its performance on-line. The function of the neural network plant emulator is to provide the correct error signal at the output of the neural fuzzy compensator without the need for any mathematical modeling of the plant. The difficulty of fine-tuning the scale factors and formulating the correct control rules in a basic fuzzy controller may be reduced using the proposed scheme. The scheme is applied to the temperature control of a water bath process. The performance of the adaptive fuzzy-neural controller is compared to the basic fuzzy logic controller and a conventional digital-PI controller under identical conditions of varying complexities in the process. The experimental results show that the adaptive fuzzy-neural control scheme is superior in performance than the other two controllers. >

Application of self-tuning PI(PID) controller to a temperature control system

Abstract: In this paper, an application of the self-tuning PI (STPI) controller, proposed by Cameron et. al (1983), to a microcomputer controlled water bath system is described. The water bath is an example of an important component in many industrial chemical processes. Experiments are conducted to test the STPI controller and to compare its performance with two other controllers, namely a self-tuning controller (STC) of Clarke and Gawthrop (1975, 1979) and a conventional PI controller. The reliability of the STPI controller is tested by artificially adding load disturbances, simulating a change in the process dynamics, and artificially adding a variable delay time element in the control loop of the process. The results prove that the performance of the STPI controller is as good as a self-tuning controller plus an added advantage of having a PI like structure. Moreover, the STPI controller performs better than the conventional PI controller especially when there are changes in the process dynamics. >

Supercritical fluid extraction and capillary gas chromatography of the rhizomes of Z. zerumbet

Abstract: Supercritical carbon dioxide at 60°C and 200 bar has been used to extract the nonpolar components of the dried rhizomes of Zingiber zerumbet. The extract could be fractionated by placing an on-line silica column before the pressure relief valve. The extracts were analyzed using capillary GC and GC-MS. This technique provides an effective means of sample preparation and a relatively fast way of determining the constituents of plant materials.

Decentralized and hierarchical control of a class of robot manipulators

Abstract: This paper is concerned with the design of robust controllers for uncertain non-linear robot manipulators based on a deterministic approach. A decentralized tracking controller is presented in which the controller is designed for each subsystem based only on its local states. For the cases in which the interconnection functions between the subsystems are large, a two-level hierarchical control strategy is proposed. In designing the controllers, only the bounds on the system uncertainties are assumed to be known. It is shown theoretically and through computer simulations that the proposed controllers guarantee uniform ultimate boundedness of the error between the reference trajectory and the system output.

Structural Characterization of Rhenium Impregnated Zeolite Y and ZSM-5 by 29Si and 27 Al MAS NMR and IR Spectroscopy

Abstract: Rhenium impregnated on zeolite catalysts is expected to provide variable acidity and selectivity towards metathesis of olefin in palm oil. Since the reactivity depends on the bondingand surface area of the catalytic system, the structural characteristics of Re impregnated zeolite Y and ZSM-5 were established by IR and MAS NMR. Three new peaks are observed at 912, 924 and 934 cm- l by IR. The first two peaks are assigned to tetrahedral and octahedral centres of the dimeric Re 2 O 7 respectively. The peak at 934 cm- 1 is assigned to distorted octahedral Re 2 0 7 formed when two oxygens of Re are bonded to the zeolite support. The impregnation of Re on the zeolite surface is further supported by 29 Si and 27 A1 MAS NMR. The number of Re 2 0 7 (mol/uc) attached on zeolite Y and ZSM-5 is 2.2 and 1.O respectively. A possible mechanism of impregnation is proposed.

Integration of experimentation and computerization

Abstract: True hands on experimentation in circuits, power, control, and electronics laboratories is an essential part of engineering education. Much can be done with simulation, but simulation does not replace the real thing. The experiments should not be bogged down with meticulous meter reading and manual plotting. A microcomputer with appropriate software and hardware is useful in reducing the tedium without distracting from the benefit of physical hands on experimentation. A system is being developed at the University of Technology in Malaysia, based on the concepts of the prototypes, object oriented and modular, to allow much greater flexibility that can be user modified to incorporate new modules and procedures as appropriate. The concept is to replace the bench full of instruments with a set of virtual instruments in a generic microcomputer. >

Variable step adaptive equalizer for digital mobile radio

Abstract: In a digital mobile radio system, an adaptive equalizer is introduced at the receiver to remove the effect of intersymbol interference. The digital mobile radio signal system requires a fast converging adaptive equalizer algorithm. The well-known conventional LMS algorithm has proven to be incapable of handling such environment. Thus, this has led into studies on other faster and more complex algorithms such as RLS and Kalman algorithm. Another alternative to these algorithms is analyzed namely the variable step LMS (VSLMS) algorithm. The performance of the VSLMS algorithm, which is based on the LMS algorithm with variable step size, is studied under a digital mobile environment. Simulation results are also presented to prove the superiority of the performance of the VSLMS algorithm compared to the LMS algorithm. >

Automatic recognition of symbols in utility maps

Abstract: A new algorithm for matching and recognizing test symbols is developed via matching segments which identify the test symbol as one of the nearest prototypes. The measures of similarity between the segment lists involve (i) the total minimum cost and (ii) the Euclidean distance. The proportion of times a test image is correctly matched to the prototype is a measure of the probability of misclassification. Preliminary results using this technique show it to be quite promising, as a recognition rate of 80-90% has been achieved. >

Structural use of coated fabric for long span roofs an overview

Abstract: One of the more visible developments in civil engineering in- the past decade has been the utilization of coated fabrics as a major structural component for roofs of large spans. Fabric roofs can now be found throughout the world covering various types of structures such as sports stadia, ice rinks, swimming pools, leisure centres and other applications. Coated fabrics are now being used extensively in hot countries to create shades. The decision to use a fabric structure can be for one a/three reasons: image, cost or some special property of the material, such as tra"lSlucency or radio transparency. II is intended thot this paper will provide an introductory overview of the.technology of modem lightweight fabric structures by means of brief description and illustration of some technical aspects of such systems

Zeolite-Rubber Blend: A composite with improved mechanical and conducting properties

Abstract: This paper presents for the first time the study on the effect of compounding zeolites into NR/HDPE blends on the structure, mechanical properties with respect to tensile strength, thermal stability and electrical resistivity The increase in efficiency of compounding and improved mechanical properties observed are associated with the particle size and framework structure of the zeolites The particle size of zeolites influences the distribution and homogeneity of the resulting NR/HDPE composite The mechanical properties such as modulus, tensile strength and % elongation at break also depend on the amount and type of zeolite added Characterization studies by MAS NMR and TG indicate that the mixing process is physical in nature and has no effect on the structure and temal properties of the resulting composite Incorporation of zeolites strongly increases the electrical resistivity of the resulting composite

Short-term salinity predictions in back bay of biloxi, mississippi

Abstract: In the development of a water quality model for Back Bay of Biloxi, the Water Quality Analysis Sirnulation-5 (WASPS) was used. The model is calibrated to a set of field data acquired on Back Bay of Biloxi, during June 14 - 16, 1977 and is verified with another set of field data taken in the Bay, during July 28 - August 2, 1972. The transport mechanisms of the estuary are modeled in each of the 376 segments of two-dimensional vertically mixed system by simulating salinity as a conservative tracer. Comparisons of the predicted and observed salinity data are made qualitatively by using spatial and temporal comparisons ,and quantitatively by statistical comparisons. The response of model prediction calculations is consistent with trends of the observed salinity data ranges, but not with absolute values in all cases. The results indicate that the model can accurately predict the concentration of salinity in the range of observed data taken at low and high tide conditions.

The Application of Pressure Drop Through a Horizontal Well Correlation to Oil Well Production Performance.

Abstract: From the petroleum engineering standpoint, pressure drop through a horizontal wellbore is very small and is negligible in predicting the production performance. However, not much research has been done to study this phenomenon and more importantly to prove the above assumption. This paper discuss the application of published pressure drop through a horizontal well correlation in the prediction of horizontal oil-well production performance. The correlation relates two-phase pressure drop along the hole to the fluid inflow from the reservoir. This correlation together with friction and hydrostatic effects were used to determine the total pressure drop from the wellhead to the well tip. The calculations by iteratively solving pressure drop along pipe equations with reservoir flow equations was done with the aid of computer program. The study proves that pressure drop is very important in predicting the inflow rate distribution along well bores especially when using small perforated rough pipes and dealing with long horizontal wellbores. References and illustrations at end of the paper INTRODUCTION Many researchers argued that multiphase flow pressure drop along horizontal oil-well can be ignored when predicting well production performance. Some of these arguments were supported by calculation of pressure drop due to pipe wall friction. This, however is not true. Fluid inflow through the perforation causes flow disturbance and momentum change along the hole, thus creating additional pressure drop (See Fig. 1). This pressure drop may affect the calculation of inflow rate distribution along the hole especially in long low drawdown wells and high permeability reservoirs. The inflow rate distribution calculation is very important when dealing with thin oil rims with underline water or/and overlying gas, where possible coning problems might occur at the highest inflow rate section. Controlling the optimum oil production rate and designing appropriate completion should be done to avoid premature water or gas breakthrough. The early study on this subject was made by Dikken1• He developed simple analytical models for single phase flow in well bores and steady state fluid flow in the reservoirs. These two models were solved simultaneously to give solutions for cases of infinite or fmite well length. The results of the study are quite interesting. It shows that the calculation of pressure drop along the horizontal hole is very 2 AZMI M. ARSHAD, MUHAMMAD A. MANAN & ABDUL R. ISMAIL SPE 28801 important especially in calculating inflow rate and production performance. The study was then followed by several others.2-7 Only correlations by Asheim et al. 8 and Arshad et al. 9 were found in literatures where simple and direct correlation describing the effect of fluid inflow through the perforation on the pressure drop along the pipe were developed. However, no application of the correlations was introduced. The focus of this study was on the use of these correlations to calculate well performance behavior. The correlations was combined with the two phase frictional effect along the pipe and coupled with the reservoir flows. Pressure drop and flow behavior along the well and the relationship between the pressure drop and the fluid inflow from the reservoir were studied. PRESSURE DROP BY FLUID INFLOW Conceptually, fluid inflow through the perforations may affect the pressure drop along the wellbore by: (a) Disturbing the boundary layer at the pipe Wall, thus altering the wall friction.8 (b) Disturbing the pipe flow pattern, thus changing the flow frictional effect, and (c) Consuming pressure energy to accelerate the inflow streams up to the average pipe flow velocity.8 Asheim et ale Correlation Asheim et al. correlation was produced from combined theoretical and experimental studies on single phase wellbore flow with fluid inflow effects due to perforations. They proposed a new flow resistance correlation combining the effect of wall friction and external fluid inflow through perforations. The external fluid inflow pressure drop correlation itself can be described by: where PI VI qi Q liquid density (kg/m3) liquid flow velocity in the pipe (mls) liquid inflow rate per length unit (m3/s/m) liquid pipe flow rate (m3/s) Arshad et ale Correlation Arshad et al. correlation is the results of two phase experimental studies and mathematical modeling. One inch inside diameter PVC pipe was used to study the effect of single and multiple perforations on pressure drop along the pipe. Eighty-one sets of data points were analyzed from the experiment that was used air and water as two phase fluids. The study proves that the effect of multiple perforations can be neglected to calculate the pressure drop. However, the volume of in situ two phase inflow rates entering the pipe controls the amount of pressure drop. The correlation developed is given by: where Ap Vg Pg qg cross-sectional area of the pipe (m2) gas flow velocity in the pipe (mls) gas density (kg/m3) gas inflow rate per length unit (rft3/s/m) In horizontal pipe flow, the difference between the velocity of liquid and gas through the pipe is very small. For that reason, the terms liquid and gas velocities can be replaced by single term named average mixture velocity. The equation then can be modified to: where Vm average mixture flow velocity of gas and liquid in the pipe (mls)

Analysis of an urban water supply by linear programming

Abstract: This study investigates the use of linear programming to determine waters distribution schedule from different sources to different water-demanding sectors as well as to determine the scheduled priority use of different types of water resources. For this purpose, the transportation and mixed integer programming algorithms are used. The formulation of both algorithms were analyzed using LINDO program. The method of linear programming (LP) is adopted to optimize water delivery schemes for Icbid City, the second largest city in Jordan. This city as well as the whole country depends mainly upon surface water, and groundwater resources which are scarce and expensive to exploit. The result of the study shows a reasonable argument where all surface water from all sources (Mukhaiba, Wadi Arab and Local supply) is used and none of the groundwater supply is diverted for agricultural purposes due to'its higher cost.