DR. MOHD HANAPIAH ABDULLAH - Academia.edu (original) (raw)

Papers by DR. MOHD HANAPIAH ABDULLAH

Research paper thumbnail of The Effect of Alum as Additive in Mix Dye for Dye Sensitized Solar Cell (DSSC)

Journal of electrical and electronic systems research, Nov 1, 2022

Dye-sensitized solar cell (DSSC) is the third-generation solar cell that first co-invented by Mic... more Dye-sensitized solar cell (DSSC) is the third-generation solar cell that first co-invented by Michael Gratzel and Brian O'Regan. In this study, TiO2 photoelectrode are sensitized with natural blackberry dye and spinach is used as co-sensitizer (mix dye). The aluminium sulphate, Al2(SO4)3 (alum) is used as the additives to treat the dye. FESEM and EDXs techniques are used to characterise the photoelectrodes, while UV-Vis and FTIR were used to examine the dye characteristics. Finally, I-V characteristic measurements were used to evaluate the performance of DSSCs. Based on the result, since of the inclusion of chlorophyll (spinach) in sensitizer, blackberry/spinach/alum performs somewhat worse than blackberry/alum because the findings on Uv Vis spectra indicates that peak of anthocyanin (blackberry) has decreased with the addition of chlorophyll (spinach). The highest efficiency (0.782%) is attained for devices that use a Blackberry/Alum sensitizer, based on device electrical parameters.

Research paper thumbnail of Formation of a Nanorod-Assembled TiO2 Actinomorphic-Flower-like Microsphere Film via Ta Doping Using a Facile Solution Immersion Method for Humidity Sensing

Nanomaterials

This study fabricated tantalum (Ta)-doped titanium dioxide with a unique nanorod-assembled actino... more This study fabricated tantalum (Ta)-doped titanium dioxide with a unique nanorod-assembled actinomorphic-flower-like microsphere structured film. The Ta-doped TiO2 actinomorphic-flower-like microsphere (TAFM) was fabricated via the solution immersion method in a Schott bottle with a home-made improvised clamp. The samples were characterised using FESEM, HRTEM, XRD, Raman, XPS, and Hall effect measurements for their structural and electrical properties. Compared to the undoped sample, the rutile-phased TAFM sample had finer nanorods with an average 42 nm diameter assembled to form microsphere-like structures. It also had higher oxygen vacancy sites, electron concentration, and mobility. In addition, a reversed double-beam photoacoustic spectroscopy measurement was performed for TAFM, revealing that the sample had a high electron trap density of up to 2.5 μmolg−1. The TAFM showed promising results when employed as the resistive-type sensing film for a humidity sensor, with the highest...

Research paper thumbnail of Optimization of Aluminum Dopant Amalgamation Immersion Time on Structural, Electrical, and Humidity-Sensing Attributes of Pristine ZnO for Flexible Humidity Sensor Application

Chemosensors

This study synthesized pristine and aluminum (Al)-doped zinc oxide (Al:ZnO) nanostructures throug... more This study synthesized pristine and aluminum (Al)-doped zinc oxide (Al:ZnO) nanostructures through a simplistic low-temperature ultrasonicated solution immersion method. Al:ZnO nanostructures were synthesized as a sensing material using different immersion times varying from two to five hours. The Al:ZnO nanostructured-based flexible humidity sensor was fabricated by employing cellulose filter paper as a substrate and transparent paper glue as a binder through a simplistic brush printing technique. XRD, FESEM, HRTEM, EDS, XPS, a two-probe I–V measurement system, and a humidity measurement system were employed to investigate the structural, morphological, chemical, electrical, and humidity-sensing properties of the pristine ZnO and Al:ZnO nanostructures. The structural and morphological analysis confirmed that Al cations successfully occupied the Zn lattice or integrated into interstitial sites of the ZnO lattice matrix. Humidity-sensing performance analysis indicated that the resist...

Research paper thumbnail of Efficient Distance Computation Algorithm between Nearly Intersected Objects Using Dynamic Pivot Point in Virtual Environment Application

Cornell University - arXiv, Oct 16, 2014

Finding nearly accurate distance between two or more nearly intersecting three-dimensional (3D) o... more Finding nearly accurate distance between two or more nearly intersecting three-dimensional (3D) objects is vital especially for collision determination such as in virtual surgeon simulation and real-time car crash simulation. Instead of performing broad phase collision detection, we need to check for accuracy of detection by running narrow phase collision detection. One of the important elements for narrow phase collision detection is to determine the precise distance between two or more nearly intersecting objects or polygons in order to prepare the area for potential colliding. Distance computation plays important roles in determine the exact point of contact between two or more nearly intersecting polygons where the preparation for collision detection is determined at the earlier stage. In this paper, we describes our current works of determining the distance between objects using dynamic pivot point that will be used as reference point to reduce the complexity searching for potential point of contacts. By using Axis-Aligned Bounding Box for each polygon, we calculate a dynamic pivot point that will become our reference point to determine the potential candidates for distance computation. The test our finding distance will be simplified by using our method instead of performing unneeded operations. Our method provides faster solution than the previous method where it helps to determine the point of contact efficiently and faster than the other method.

Research paper thumbnail of Speech-based gender recognition using linear prediction and mel-frequency cepstral coefficients

Indonesian Journal of Electrical Engineering and Computer Science

Gender discrimination and awareness are essentially practiced in social, education, workplace, an... more Gender discrimination and awareness are essentially practiced in social, education, workplace, and economic sectors across the globe. A person manifests this attribute naturally in gait, body gesture, facial, including speech. For that reason, automatic gender recognition (AGR) has become an interesting sub-topic in speech recognition systems that can be found in many speech technology applications. However, retrieving salient gender-related information from a speech signal is a challenging problem since speech contains abundant information apart from gender. The paper intends to compare the performance of human vocal tract-based model i.e., linear prediction coefficients (LPC) and human auditory-based model i.e., Mel-frequency cepstral coefficients (MFCC) which are popularly used in other speech recognition tasks by experimentation of optimal feature parameters and classifier’s parameters. The audio data used in this study was obtained from 93 speakers uttering selected words with ...

Research paper thumbnail of Optical absorbance of RGB LEDs in pH measurement of colorimetric solution with phenol red reagent

Indonesian Journal of Electrical Engineering and Computer Science

The use of red, green, and blue ( RGB ) light-emitting-diode ( LED ) is a new trend in monochroma... more The use of red, green, and blue ( RGB ) light-emitting-diode ( LED ) is a new trend in monochromatic colorimetric sensing due to cost-effective implementation. However, the application of RGB LED in pH measurement depends on the performance of the LED colour towards the colorimetric solution of interest, hence, needs to be evaluated. This work evaluated the performance of RGB LED for pH measurement system based on colorimetric approach using phenol red as a reagent. The main objective was to identify the LED colour with the best performance in terms of signal response and a bsorbance behavior. In this work, LED and photodiode were used as optical components and NI USB DAQ with LabView as the processing software. Four samples with known pH values were prepared and tested to obtain the voltage and absorbance behavior of each LED colour. Among all, the blue LED with wavelength ranged between 450 - 495 nm showed the best sensing behavior based on its linearity and error. Both voltage re...

Research paper thumbnail of Swing-up Control of Mass Body Interlinked Flexible Tether

Archive of Mechanical Engineering, 2010

SWING-UP CONTROL OF MASS BODY INTERLINKED FLEXIBLE TETHER One of the applications of tether syste... more SWING-UP CONTROL OF MASS BODY INTERLINKED FLEXIBLE TETHER One of the applications of tether system is in the field of satellite technology, where the mother ship and satellite equipment are connected with a cable. In order to grasp the motion of this kind of tether system in detail, the tether can be effectively modeled as flexible body and dealt by multibody dynamic analysis. In the analysis and modeling of flexible body of tether, large deformation and large displacement must be considered. Multibody dynamic analysis such as Absolute Nodal Coordinate Formulation with an introduction of the effect of damping force formulation can be used to describe the motion behavior of a flexible body. In this study, a parameter identification technique via an experimental approach is proposed in order to verify the modeling method. An example of swing-up control using the genetic algorithm control approach is performed through simulation and experiment. The validity of the model and availability of motion control based on multibody dynamics analysis are shown by comparison between numerical simulation and experiment.

Research paper thumbnail of Groundwater challenges in small islands: a review and examples from Malaysia

Research paper thumbnail of Sustainable groundwater management on the small island of Manukan, Malaysia

Environmental Earth Sciences, 2012

Numerical models are capable of simulating various groundwater scenarios and relate it towards gr... more Numerical models are capable of simulating various groundwater scenarios and relate it towards groundwater management. This paper focuses on numerical modeling and water balance approaches in the search for a sustainable management plan in Manukan Island. The impacts of pumping and recharge rates represented by groundwater scenarios were investigated by means of hydraulic heads, chloride concentrations and water balance components. Overpumping and inconsistency in recharge rate are the stresses shown in Scenario A. Scenario B involved with reduction pumping rate by 25% has shown an increase in groundwater levels, chloride concentration and groundwater storage. Scenario C showed the most promising finding compared with Scenarios A and B. Highest hydraulic heads, lowest chloride concentration (1,552.2 mg/L) and positive groundwater storage (254.3 m 3/day) were obtained in Scenario C. Chloride concentration in pumping wells still exceeds World Health Organization International Standard limit in Scenario C which illustrates an additional water treatment is needed. Nevertheless, in view of a compromise groundwater management plan in study area, Scenario C is the best plan so far to protect the groundwater resources in the study area. More understanding of the artificial recharge method (percolation tank) and study site by means of modeling studies is needed. Additionally, further progress is needed in obtaining the water usage data from each part to determine the best pumping rate. A sustainable groundwater management plan is crucial to maintain the natural resources and social benefits as well as to protect the ecological balance of Manukan Island.

Research paper thumbnail of Developing a UML Profile for Modelling Knowledge-Based Systems

Lecture Notes in Computer Science, 2005

Knowledge engineers have favoured a diagrammatic approach for developing knowledge-based systems ... more Knowledge engineers have favoured a diagrammatic approach for developing knowledge-based systems by adopting those used in software engineering. However, these modelling techniques tend to be used in an ad hoc way and are highly dependent on the modelling experience of the engineers involved. This paper focuses on the use of the Unified Modeling Language (UML) Profiles for knowledge modelling. It identifies the shortcomings of current approaches in adopting UML and discusses the need to have an extension to UML through the profile mechanism. A work-in-progress on creating such a profile is also presented.

Research paper thumbnail of Knowledge Modelling Using The UML Profile

IFIP International Federation for Information Processing

This paper discusses platform independent conceptual modeling of a knowledge intensive applicatio... more This paper discusses platform independent conceptual modeling of a knowledge intensive application, focusing on the use of knowledge-based systems (KBS) in the context of model-driven engineering. An extension to the Unified Modeling Language (UML) for knowledge modeling is presented based on the profiling extension mechanism of UML. The UML profile discussed in this paper has been successfully captured in a Meta-Object-Facility (MOP) based UML tool-the executable Modeling Framework (XMF). The example is that of modeling a knowledge-based system for the Ulcer Clinical Practical Guidelines (CPG) Recommendations. It demonstrates the use of the profile, with the prototype system implemented in the Java Expert System Shell (JESS).

Research paper thumbnail of hcc —a portable ANSI C compiler (with a code generator for the PowerPCs)

ACM SIGPLAN Notices, 1996

hcc is a portable optimizing compiler for ANSI C [8] [9] with code generators for the PowerPC and... more hcc is a portable optimizing compiler for ANSI C [8] [9] with code generators for the PowerPC and the MIMOS's RISC CPU. The PowerPC is a RISC processor developed jointly by IBM, Motorola, and Apple Computer among others in 1993, while the MIMOS's RISC CPU is an experimental 32-bit RISC processor. At the moment the compiler can be used to program PowerPC based computers including the PowerMacintoshes and the IBM RS6000 PowerPC based workstations.

Research paper thumbnail of Quad Separation Algorithm for Bounding-Volume Hierarchies Construction in Virtual Environment Application

Journal of Next Generation Information Technology, 2013

In order to perform fast collision detection technique in Virtual Environment Application, resear... more In order to perform fast collision detection technique in Virtual Environment Application, researchers need to maintain the behaviour of the object itself before the objects come into contact. By enhancing the speed of intersection using Bounding-Volume Hierarchies technique, it helps to reduce the complexity and speed up the intersection process. Thus, in this paper we presented our novel algorithm for constructing Bounding-Volume Hierarchies using Quad Splitting method. Together with the Quad Splitting method is the implementation of Spatial Object Median Splitting technique (SOMS) in order to create a well-balanced tree for the object. We believed the key of performing fast intersection between two or more objects in Virtual Environment Application required a well-balanced and proper tree technique for Bounding-Volume hierarchies.

Research paper thumbnail of Study on Combustion Performance of Palm Oil Biodiesel Blend

Jurnal Teknologi, 2014

The world today is adversely affected by the rapid growth of various industries which use fossil ... more The world today is adversely affected by the rapid growth of various industries which use fossil diesel fuel as a main source to power their respective industries. As such, these natural resources are increasingly reduced thus resulting in price increments. A study was conducted to find a way to develop alternative energy sources that are environmentally friendly and renewable. One of the potential sources of energy is palm oil. Therefore, this project is intended to look at the effect of combustion of biodiesel from palm oil which is carotino palm oil. This project will include the study of the physical characteristics of the fuel such as density, viscosity, and surface tension. In terms of combustion, it includes emissions during the combustion process, the temperature profile and the flame length. Several carotino biodiesel blends have been made, i.e. B0, B10, B20, B30, B40, B50, and B100 whereby each blend will be burned in the combustion chamber in three conditions which are at...

Research paper thumbnail of Groundwater Assessment at Manukan Island, Sabah: Multidisplinary Approaches

Natural Resources Research, 2010

A rapid increase in the number of tourists has placed a heavy demand for freshwater on Manukan Is... more A rapid increase in the number of tourists has placed a heavy demand for freshwater on Manukan Island, a small island located offcoast of Kota Kinabalu, Sabah. Hydrochemical and numerical approaches have been applied in this study to evaluate the groundwater quality of unconfined aquifer lying in Manukan Island, Sabah, East Malaysia. This is vital

Research paper thumbnail of Stability Behavior and Thermodynamic States of Iron and Manganese in Sandy Soil Aquifer, Manukan Island, Malaysia

Natural Resources Research, 2011

A total of 20 soil samples were collected from 10 boreholes constructed in the low lying area, wh... more A total of 20 soil samples were collected from 10 boreholes constructed in the low lying area, which included ancillary samples taken from the high elevation area. Redox processes were investigated in the soil as well as groundwater in the shallow groundwater aquifer of Manukan Island, Sabah, Malaysia. Groundwater samples (n = 10) from each boreholes were also collected in the low lying area to understand the concentrations and behaviors of Fe and Mn in the dissolved state. This study strives to obtain a general understanding of the stability behaviors on Fe and Mn at the upper unsaturated and the lower-saturated soil horizons in the low lying area of Manukan Island as these elements usually play a major role in the redox chemistry of the shallow groundwater. Thermodynamic calculations using PHREEQC showed that the groundwater samples in the study area are oversaturated with respect to goethite, hematite, Fe(OH)3 and undersaturated with respect to manganite and pyrochroite. Low concentrations of Fe and Mn in the groundwater might be probably due to the lack of minerals of iron and manganese oxides, which exist in the sandy aquifer. In fact, high organic matters that present in the unsaturated horizon are believed to be responsible for the high Mn content in the soil. It was observed that the soil samples collected from high elevation area (BK) comprises considerable amount of Fe in both unsaturated (6675.87 mg/kg) and saturated horizons (31440.49 mg/kg) compared to the low Fe content in the low lying area. Based on the stability diagram, the groundwater composition lies within the stability field for Mn2+ and Fe2+ under suboxic condition and very close to the FeS/Fe2+ stability boundary. This study also shows that both pH and Eh values comprise a strong negative value thus suggesting that the redox potential is inversely dependent on the changes of pH.

Research paper thumbnail of System Identification of Railway Trains Pantograph for Active Pantograph Simulation

Journal of System Design and Dynamics, 2011

High performance of the contact wire and pantograph dynamic interaction is required in the operat... more High performance of the contact wire and pantograph dynamic interaction is required in the operation of high speed railway vehicles. Due to the constraint of field test, simulation and lab experiment procedures are performable to verify the interaction. Such simulation needs accurate modeling of the response of the pantograph for the consistency in prediction and control. A simple system identification of the pantograph is executed based on the lab experimental data using commercial software and least squares method. The validation of the procedure is performed through comparison between extended experimental data and numerical simulations of the pantograph system. Further analysis is by applying active pantograph control on the system by simulation. The results show availability of the design for active pantograph system.

Research paper thumbnail of Numerical simulation of seawater intrusion in Manukan Island, East Malaysia

Journal of Modelling in Management, 2011

PurposeThis paper aims to define the current and potential extent of seawater intrusion in Manuka... more PurposeThis paper aims to define the current and potential extent of seawater intrusion in Manukan Island under different scenarios of varying recharge and pumping rates. The calibrated model was also used to predict the extent of seawater intrusion in low lying area of Manukan Island for two years with all conditions assumed to remain the same as those in December 2009.Design/methodology/approachDifferent scenarios of varying recharge and pumping rates based on threats received by Manukan Island were investigated. El‐Nino events and overpumping are represented by varying recharge and pumping rates. Simulation was done using SEAWAT‐2000, the latest modeling software available in groundwater modeling that couples flow and transport together.FindingsThe seawater‐freshwater mixing ratio moves landwards after two years of simulation in Scenario 1. In order to control overpumping in this study area, Scenario 2 has resulted in backward movement of the 1.4 percent seawater‐freshwater mixin...

Research paper thumbnail of Delineation of temporal variability and governing factors influencing the spatial variability of shallow groundwater chemistry in a tropical sedimentary island

Journal of Hydrology, 2012

An attempt has been made to delineate the temporal variability and factors governing the shallow ... more An attempt has been made to delineate the temporal variability and factors governing the shallow groundwater chemistry using analysis of variance (ANOVA) and multivariate analysis notably R-mode factor (FA) and hierarchical cluster analysis (HCA). Subsequently, geostatistical isoplethic maps were applied to convey better understanding on the distribution of selected groundwater parameters. The Manukan

Research paper thumbnail of The Influence of Seawater on the Chemical Composition of Groundwater in a Small Island: The Example of Manukan Island, East Malaysia

Journal of Coastal Research, 2012

Manukan Island in Sabah, Malaysia, is characterized as a small, unique island where groundwater i... more Manukan Island in Sabah, Malaysia, is characterized as a small, unique island where groundwater is a major source for domestic water and other water-related activities. Hydrochemical studies were carried out in the island with the objective of identifying the influence of seawater on the chemical composition of groundwater in Manukan

Research paper thumbnail of The Effect of Alum as Additive in Mix Dye for Dye Sensitized Solar Cell (DSSC)

Journal of electrical and electronic systems research, Nov 1, 2022

Dye-sensitized solar cell (DSSC) is the third-generation solar cell that first co-invented by Mic... more Dye-sensitized solar cell (DSSC) is the third-generation solar cell that first co-invented by Michael Gratzel and Brian O'Regan. In this study, TiO2 photoelectrode are sensitized with natural blackberry dye and spinach is used as co-sensitizer (mix dye). The aluminium sulphate, Al2(SO4)3 (alum) is used as the additives to treat the dye. FESEM and EDXs techniques are used to characterise the photoelectrodes, while UV-Vis and FTIR were used to examine the dye characteristics. Finally, I-V characteristic measurements were used to evaluate the performance of DSSCs. Based on the result, since of the inclusion of chlorophyll (spinach) in sensitizer, blackberry/spinach/alum performs somewhat worse than blackberry/alum because the findings on Uv Vis spectra indicates that peak of anthocyanin (blackberry) has decreased with the addition of chlorophyll (spinach). The highest efficiency (0.782%) is attained for devices that use a Blackberry/Alum sensitizer, based on device electrical parameters.

Research paper thumbnail of Formation of a Nanorod-Assembled TiO2 Actinomorphic-Flower-like Microsphere Film via Ta Doping Using a Facile Solution Immersion Method for Humidity Sensing

Nanomaterials

This study fabricated tantalum (Ta)-doped titanium dioxide with a unique nanorod-assembled actino... more This study fabricated tantalum (Ta)-doped titanium dioxide with a unique nanorod-assembled actinomorphic-flower-like microsphere structured film. The Ta-doped TiO2 actinomorphic-flower-like microsphere (TAFM) was fabricated via the solution immersion method in a Schott bottle with a home-made improvised clamp. The samples were characterised using FESEM, HRTEM, XRD, Raman, XPS, and Hall effect measurements for their structural and electrical properties. Compared to the undoped sample, the rutile-phased TAFM sample had finer nanorods with an average 42 nm diameter assembled to form microsphere-like structures. It also had higher oxygen vacancy sites, electron concentration, and mobility. In addition, a reversed double-beam photoacoustic spectroscopy measurement was performed for TAFM, revealing that the sample had a high electron trap density of up to 2.5 μmolg−1. The TAFM showed promising results when employed as the resistive-type sensing film for a humidity sensor, with the highest...

Research paper thumbnail of Optimization of Aluminum Dopant Amalgamation Immersion Time on Structural, Electrical, and Humidity-Sensing Attributes of Pristine ZnO for Flexible Humidity Sensor Application

Chemosensors

This study synthesized pristine and aluminum (Al)-doped zinc oxide (Al:ZnO) nanostructures throug... more This study synthesized pristine and aluminum (Al)-doped zinc oxide (Al:ZnO) nanostructures through a simplistic low-temperature ultrasonicated solution immersion method. Al:ZnO nanostructures were synthesized as a sensing material using different immersion times varying from two to five hours. The Al:ZnO nanostructured-based flexible humidity sensor was fabricated by employing cellulose filter paper as a substrate and transparent paper glue as a binder through a simplistic brush printing technique. XRD, FESEM, HRTEM, EDS, XPS, a two-probe I–V measurement system, and a humidity measurement system were employed to investigate the structural, morphological, chemical, electrical, and humidity-sensing properties of the pristine ZnO and Al:ZnO nanostructures. The structural and morphological analysis confirmed that Al cations successfully occupied the Zn lattice or integrated into interstitial sites of the ZnO lattice matrix. Humidity-sensing performance analysis indicated that the resist...

Research paper thumbnail of Efficient Distance Computation Algorithm between Nearly Intersected Objects Using Dynamic Pivot Point in Virtual Environment Application

Cornell University - arXiv, Oct 16, 2014

Finding nearly accurate distance between two or more nearly intersecting three-dimensional (3D) o... more Finding nearly accurate distance between two or more nearly intersecting three-dimensional (3D) objects is vital especially for collision determination such as in virtual surgeon simulation and real-time car crash simulation. Instead of performing broad phase collision detection, we need to check for accuracy of detection by running narrow phase collision detection. One of the important elements for narrow phase collision detection is to determine the precise distance between two or more nearly intersecting objects or polygons in order to prepare the area for potential colliding. Distance computation plays important roles in determine the exact point of contact between two or more nearly intersecting polygons where the preparation for collision detection is determined at the earlier stage. In this paper, we describes our current works of determining the distance between objects using dynamic pivot point that will be used as reference point to reduce the complexity searching for potential point of contacts. By using Axis-Aligned Bounding Box for each polygon, we calculate a dynamic pivot point that will become our reference point to determine the potential candidates for distance computation. The test our finding distance will be simplified by using our method instead of performing unneeded operations. Our method provides faster solution than the previous method where it helps to determine the point of contact efficiently and faster than the other method.

Research paper thumbnail of Speech-based gender recognition using linear prediction and mel-frequency cepstral coefficients

Indonesian Journal of Electrical Engineering and Computer Science

Gender discrimination and awareness are essentially practiced in social, education, workplace, an... more Gender discrimination and awareness are essentially practiced in social, education, workplace, and economic sectors across the globe. A person manifests this attribute naturally in gait, body gesture, facial, including speech. For that reason, automatic gender recognition (AGR) has become an interesting sub-topic in speech recognition systems that can be found in many speech technology applications. However, retrieving salient gender-related information from a speech signal is a challenging problem since speech contains abundant information apart from gender. The paper intends to compare the performance of human vocal tract-based model i.e., linear prediction coefficients (LPC) and human auditory-based model i.e., Mel-frequency cepstral coefficients (MFCC) which are popularly used in other speech recognition tasks by experimentation of optimal feature parameters and classifier’s parameters. The audio data used in this study was obtained from 93 speakers uttering selected words with ...

Research paper thumbnail of Optical absorbance of RGB LEDs in pH measurement of colorimetric solution with phenol red reagent

Indonesian Journal of Electrical Engineering and Computer Science

The use of red, green, and blue ( RGB ) light-emitting-diode ( LED ) is a new trend in monochroma... more The use of red, green, and blue ( RGB ) light-emitting-diode ( LED ) is a new trend in monochromatic colorimetric sensing due to cost-effective implementation. However, the application of RGB LED in pH measurement depends on the performance of the LED colour towards the colorimetric solution of interest, hence, needs to be evaluated. This work evaluated the performance of RGB LED for pH measurement system based on colorimetric approach using phenol red as a reagent. The main objective was to identify the LED colour with the best performance in terms of signal response and a bsorbance behavior. In this work, LED and photodiode were used as optical components and NI USB DAQ with LabView as the processing software. Four samples with known pH values were prepared and tested to obtain the voltage and absorbance behavior of each LED colour. Among all, the blue LED with wavelength ranged between 450 - 495 nm showed the best sensing behavior based on its linearity and error. Both voltage re...

Research paper thumbnail of Swing-up Control of Mass Body Interlinked Flexible Tether

Archive of Mechanical Engineering, 2010

SWING-UP CONTROL OF MASS BODY INTERLINKED FLEXIBLE TETHER One of the applications of tether syste... more SWING-UP CONTROL OF MASS BODY INTERLINKED FLEXIBLE TETHER One of the applications of tether system is in the field of satellite technology, where the mother ship and satellite equipment are connected with a cable. In order to grasp the motion of this kind of tether system in detail, the tether can be effectively modeled as flexible body and dealt by multibody dynamic analysis. In the analysis and modeling of flexible body of tether, large deformation and large displacement must be considered. Multibody dynamic analysis such as Absolute Nodal Coordinate Formulation with an introduction of the effect of damping force formulation can be used to describe the motion behavior of a flexible body. In this study, a parameter identification technique via an experimental approach is proposed in order to verify the modeling method. An example of swing-up control using the genetic algorithm control approach is performed through simulation and experiment. The validity of the model and availability of motion control based on multibody dynamics analysis are shown by comparison between numerical simulation and experiment.

Research paper thumbnail of Groundwater challenges in small islands: a review and examples from Malaysia

Research paper thumbnail of Sustainable groundwater management on the small island of Manukan, Malaysia

Environmental Earth Sciences, 2012

Numerical models are capable of simulating various groundwater scenarios and relate it towards gr... more Numerical models are capable of simulating various groundwater scenarios and relate it towards groundwater management. This paper focuses on numerical modeling and water balance approaches in the search for a sustainable management plan in Manukan Island. The impacts of pumping and recharge rates represented by groundwater scenarios were investigated by means of hydraulic heads, chloride concentrations and water balance components. Overpumping and inconsistency in recharge rate are the stresses shown in Scenario A. Scenario B involved with reduction pumping rate by 25% has shown an increase in groundwater levels, chloride concentration and groundwater storage. Scenario C showed the most promising finding compared with Scenarios A and B. Highest hydraulic heads, lowest chloride concentration (1,552.2 mg/L) and positive groundwater storage (254.3 m 3/day) were obtained in Scenario C. Chloride concentration in pumping wells still exceeds World Health Organization International Standard limit in Scenario C which illustrates an additional water treatment is needed. Nevertheless, in view of a compromise groundwater management plan in study area, Scenario C is the best plan so far to protect the groundwater resources in the study area. More understanding of the artificial recharge method (percolation tank) and study site by means of modeling studies is needed. Additionally, further progress is needed in obtaining the water usage data from each part to determine the best pumping rate. A sustainable groundwater management plan is crucial to maintain the natural resources and social benefits as well as to protect the ecological balance of Manukan Island.

Research paper thumbnail of Developing a UML Profile for Modelling Knowledge-Based Systems

Lecture Notes in Computer Science, 2005

Knowledge engineers have favoured a diagrammatic approach for developing knowledge-based systems ... more Knowledge engineers have favoured a diagrammatic approach for developing knowledge-based systems by adopting those used in software engineering. However, these modelling techniques tend to be used in an ad hoc way and are highly dependent on the modelling experience of the engineers involved. This paper focuses on the use of the Unified Modeling Language (UML) Profiles for knowledge modelling. It identifies the shortcomings of current approaches in adopting UML and discusses the need to have an extension to UML through the profile mechanism. A work-in-progress on creating such a profile is also presented.

Research paper thumbnail of Knowledge Modelling Using The UML Profile

IFIP International Federation for Information Processing

This paper discusses platform independent conceptual modeling of a knowledge intensive applicatio... more This paper discusses platform independent conceptual modeling of a knowledge intensive application, focusing on the use of knowledge-based systems (KBS) in the context of model-driven engineering. An extension to the Unified Modeling Language (UML) for knowledge modeling is presented based on the profiling extension mechanism of UML. The UML profile discussed in this paper has been successfully captured in a Meta-Object-Facility (MOP) based UML tool-the executable Modeling Framework (XMF). The example is that of modeling a knowledge-based system for the Ulcer Clinical Practical Guidelines (CPG) Recommendations. It demonstrates the use of the profile, with the prototype system implemented in the Java Expert System Shell (JESS).

Research paper thumbnail of hcc —a portable ANSI C compiler (with a code generator for the PowerPCs)

ACM SIGPLAN Notices, 1996

hcc is a portable optimizing compiler for ANSI C [8] [9] with code generators for the PowerPC and... more hcc is a portable optimizing compiler for ANSI C [8] [9] with code generators for the PowerPC and the MIMOS's RISC CPU. The PowerPC is a RISC processor developed jointly by IBM, Motorola, and Apple Computer among others in 1993, while the MIMOS's RISC CPU is an experimental 32-bit RISC processor. At the moment the compiler can be used to program PowerPC based computers including the PowerMacintoshes and the IBM RS6000 PowerPC based workstations.

Research paper thumbnail of Quad Separation Algorithm for Bounding-Volume Hierarchies Construction in Virtual Environment Application

Journal of Next Generation Information Technology, 2013

In order to perform fast collision detection technique in Virtual Environment Application, resear... more In order to perform fast collision detection technique in Virtual Environment Application, researchers need to maintain the behaviour of the object itself before the objects come into contact. By enhancing the speed of intersection using Bounding-Volume Hierarchies technique, it helps to reduce the complexity and speed up the intersection process. Thus, in this paper we presented our novel algorithm for constructing Bounding-Volume Hierarchies using Quad Splitting method. Together with the Quad Splitting method is the implementation of Spatial Object Median Splitting technique (SOMS) in order to create a well-balanced tree for the object. We believed the key of performing fast intersection between two or more objects in Virtual Environment Application required a well-balanced and proper tree technique for Bounding-Volume hierarchies.

Research paper thumbnail of Study on Combustion Performance of Palm Oil Biodiesel Blend

Jurnal Teknologi, 2014

The world today is adversely affected by the rapid growth of various industries which use fossil ... more The world today is adversely affected by the rapid growth of various industries which use fossil diesel fuel as a main source to power their respective industries. As such, these natural resources are increasingly reduced thus resulting in price increments. A study was conducted to find a way to develop alternative energy sources that are environmentally friendly and renewable. One of the potential sources of energy is palm oil. Therefore, this project is intended to look at the effect of combustion of biodiesel from palm oil which is carotino palm oil. This project will include the study of the physical characteristics of the fuel such as density, viscosity, and surface tension. In terms of combustion, it includes emissions during the combustion process, the temperature profile and the flame length. Several carotino biodiesel blends have been made, i.e. B0, B10, B20, B30, B40, B50, and B100 whereby each blend will be burned in the combustion chamber in three conditions which are at...

Research paper thumbnail of Groundwater Assessment at Manukan Island, Sabah: Multidisplinary Approaches

Natural Resources Research, 2010

A rapid increase in the number of tourists has placed a heavy demand for freshwater on Manukan Is... more A rapid increase in the number of tourists has placed a heavy demand for freshwater on Manukan Island, a small island located offcoast of Kota Kinabalu, Sabah. Hydrochemical and numerical approaches have been applied in this study to evaluate the groundwater quality of unconfined aquifer lying in Manukan Island, Sabah, East Malaysia. This is vital

Research paper thumbnail of Stability Behavior and Thermodynamic States of Iron and Manganese in Sandy Soil Aquifer, Manukan Island, Malaysia

Natural Resources Research, 2011

A total of 20 soil samples were collected from 10 boreholes constructed in the low lying area, wh... more A total of 20 soil samples were collected from 10 boreholes constructed in the low lying area, which included ancillary samples taken from the high elevation area. Redox processes were investigated in the soil as well as groundwater in the shallow groundwater aquifer of Manukan Island, Sabah, Malaysia. Groundwater samples (n = 10) from each boreholes were also collected in the low lying area to understand the concentrations and behaviors of Fe and Mn in the dissolved state. This study strives to obtain a general understanding of the stability behaviors on Fe and Mn at the upper unsaturated and the lower-saturated soil horizons in the low lying area of Manukan Island as these elements usually play a major role in the redox chemistry of the shallow groundwater. Thermodynamic calculations using PHREEQC showed that the groundwater samples in the study area are oversaturated with respect to goethite, hematite, Fe(OH)3 and undersaturated with respect to manganite and pyrochroite. Low concentrations of Fe and Mn in the groundwater might be probably due to the lack of minerals of iron and manganese oxides, which exist in the sandy aquifer. In fact, high organic matters that present in the unsaturated horizon are believed to be responsible for the high Mn content in the soil. It was observed that the soil samples collected from high elevation area (BK) comprises considerable amount of Fe in both unsaturated (6675.87 mg/kg) and saturated horizons (31440.49 mg/kg) compared to the low Fe content in the low lying area. Based on the stability diagram, the groundwater composition lies within the stability field for Mn2+ and Fe2+ under suboxic condition and very close to the FeS/Fe2+ stability boundary. This study also shows that both pH and Eh values comprise a strong negative value thus suggesting that the redox potential is inversely dependent on the changes of pH.

Research paper thumbnail of System Identification of Railway Trains Pantograph for Active Pantograph Simulation

Journal of System Design and Dynamics, 2011

High performance of the contact wire and pantograph dynamic interaction is required in the operat... more High performance of the contact wire and pantograph dynamic interaction is required in the operation of high speed railway vehicles. Due to the constraint of field test, simulation and lab experiment procedures are performable to verify the interaction. Such simulation needs accurate modeling of the response of the pantograph for the consistency in prediction and control. A simple system identification of the pantograph is executed based on the lab experimental data using commercial software and least squares method. The validation of the procedure is performed through comparison between extended experimental data and numerical simulations of the pantograph system. Further analysis is by applying active pantograph control on the system by simulation. The results show availability of the design for active pantograph system.

Research paper thumbnail of Numerical simulation of seawater intrusion in Manukan Island, East Malaysia

Journal of Modelling in Management, 2011

PurposeThis paper aims to define the current and potential extent of seawater intrusion in Manuka... more PurposeThis paper aims to define the current and potential extent of seawater intrusion in Manukan Island under different scenarios of varying recharge and pumping rates. The calibrated model was also used to predict the extent of seawater intrusion in low lying area of Manukan Island for two years with all conditions assumed to remain the same as those in December 2009.Design/methodology/approachDifferent scenarios of varying recharge and pumping rates based on threats received by Manukan Island were investigated. El‐Nino events and overpumping are represented by varying recharge and pumping rates. Simulation was done using SEAWAT‐2000, the latest modeling software available in groundwater modeling that couples flow and transport together.FindingsThe seawater‐freshwater mixing ratio moves landwards after two years of simulation in Scenario 1. In order to control overpumping in this study area, Scenario 2 has resulted in backward movement of the 1.4 percent seawater‐freshwater mixin...

Research paper thumbnail of Delineation of temporal variability and governing factors influencing the spatial variability of shallow groundwater chemistry in a tropical sedimentary island

Journal of Hydrology, 2012

An attempt has been made to delineate the temporal variability and factors governing the shallow ... more An attempt has been made to delineate the temporal variability and factors governing the shallow groundwater chemistry using analysis of variance (ANOVA) and multivariate analysis notably R-mode factor (FA) and hierarchical cluster analysis (HCA). Subsequently, geostatistical isoplethic maps were applied to convey better understanding on the distribution of selected groundwater parameters. The Manukan

Research paper thumbnail of The Influence of Seawater on the Chemical Composition of Groundwater in a Small Island: The Example of Manukan Island, East Malaysia

Journal of Coastal Research, 2012

Manukan Island in Sabah, Malaysia, is characterized as a small, unique island where groundwater i... more Manukan Island in Sabah, Malaysia, is characterized as a small, unique island where groundwater is a major source for domestic water and other water-related activities. Hydrochemical studies were carried out in the island with the objective of identifying the influence of seawater on the chemical composition of groundwater in Manukan