Pusat Pengajian Kejuruteraan Mekanikal - Tesis

Browse

Now showing 1 - 20 of 94

A Model For The Fuzzy Front End Of New Product Development Process
(2016-01)
Abd Rahman, Md Nizam
In general, New Product Development (NPD) methodology can be broken down into five phases, Strategic Planning. Idea Generation, Pretechnical Evaluation, Technical Development, and Commercialization. The first three steps are known as the front end and the last two are known as the back-end of the NPD methodology. The scope of this research work is limited to the first two steps of the NPD methodology, which are strategic planning and idea generation. The objectives of this research work are I) to piece together the various steps required in executing strategic planning process to ensure its effectiveness and 2) to define guidelines in selecting idea generation techniques that are suitable for a given set of conditions. Through analyzing case studies on thirty cornpapies that have been proven successful in NPD programs, the main factors that have significant impact on the success of NPD strategic planning process are verified and guidelines for selecting suitable idea generation techniques for a given set of conditions are developed.
A study of punch-die misalignment in square cup deep drawing process using experiment and finite element analysis
(2022-09-01)
Abdul Ghafar, Alimi
Square deep drawing is a forming process that transforms a flat sheet metal to a seamless vessel by using a set of punch and die. Any misalignment in the punch -die assembly during the process can cause thinning, which can result in the tearing of the drawn part. The onset of thinning due to punch-die misalignment is yet to be explored fully, thus understanding the thinning initiation will be useful for process optimization. In this study, a series of comprehensive methods to identify the presence of punch-die misalignment in square cup deep drawing process is implemented. These methods are deployed at the pre-drawing, during the drawing process and at the post drawing stage. In the pre-drawing stage, an image processing technique is utilized forpre-drawiing inspection. The captured images are analysed to identify the severity of misalignment between the punch and the die. At the second stage (during forming), an in-situ method is used to observe the presence of punch-die misalignment. For this purpose, a customised die rig is fabricated and installed on a universal tensile machine (UTM). A Commercial Electrolytic Zinc-Coated Steel Sheet (SECC) was used as the specimen for the deep drawing process, and the effect of misalignment severity on drawing force and wall thickness distribution are investigated. For comparison, a finite element (FE) simulation is utilized as an early prediction of the punch-die misalignment. The simulation was conducted using Abaqus/Explicit FEA software, utilitising the Hill’48 model, to determine the stress-strain diagram and forming limit diagram (FLD) of the SECC material. Two conditions of misalignment were simulated, 1) single axis punch-die misalignment and 2) multi axes punch-die misalignment with the misalignment severity of 0.1 mm to 0.5 mm. At the post-drawing stage, the wall thickness distributions of the cup for each misalignment conditions were investigated. Variations in wall thickness distributions would indicate the severity of misalignment between the punch and die. Specifically, a novel methods are introduced for detecting the presence of punch-die misalignment in square cup deep drawing process. Both the FE and experimental results were in good agreement with regard to the drawing forces and thinning patterns due to punch-die misalignment. Greater misalignment severity was observed to increase the drawing force and thinning in the wall of the drawn cup. For both misalignment conditions, similar wall thickness distribution patterns were observed, with the maximum thinning occurring in the cup sidewall and minimal thinning at the bottom of the cup. For single axis misalignment, the maximum thickening up to 18% has occured at the lowest misalignment severity of 0.1 mm. On the other hand, for misalignment severity of 0.3 mm and above, the maximum thinning in the x-axis was higher as compared to the y-axis by average of 0.53% and 1.72% based on FE and experimental results, respectively. For multi axes misalignment, the maximum thickening averages at 15%, while the thinning was more pronounced in the rolling direction as compared to the transverse direction. As a conclusion, this study had contribute a positive signification implication in die making, especially punch-die alignment issue in deep drawing process. Alignment punch-die is essential in square cup deep drawing process. A series of comprehensive approach for identifying punch-die misalignment issue according to this study can be referred by researcher and industrial practioner in making high quality square cup deep drawn product.
A study on low temperature synthesis of silicon carbide thermionic cathode and its electron emission analysis for thermionic energy converter
(2020-07-01)
Leong, Thye Jien
Energy conversion of renewable and clean energy such as thermal energy is often related to solar cell and photovoltaic cell. These are the rising technology devices that generate electrical energy for the use in industrial and residential sectors. In order to seek for an alternative approach in meeting the growing energy demand and reducing the dependency on conventional energy resources such as biomass energy, another direct thermal energy to electricity conversion device namely Thermionic Energy Converter (TEC) is being studied. However, the technology involved in this device has one major limitation which is the unavailability of low cost cathode materials with low work function yet easily-obtained. This drawback has motivated the study of cathode material in term of lowering the work function by surface nanostructuring the thermionic cathode for TEC in the mentioned research direction. By using atmospheric pressure chemical vapor deposition (APCVD) method, a low temperature (600°C) synthesis thermionic cathode was developed, as validated by the literature (Xi et al., 2006). In this approach, silicon carbide (SiC) nanostructures were synthesized on the silicon substrate. This method was optimized based on two parameters which are controlling the thickness of catalyst (Magnesium) and the amount of precursors (silicon tetrachloride and 2-ethoxyethanol) used in the experiments. Some material characterization techniques, such as SEM, EDX, and FESEM were performed to the thermionic cathode to support the proposed synthesis method. Besides, a new in-house built TEC system that is equipped with a vacuum chamber, CO2 laser heating system, turbomolecular pump, and digital nanoammeter was developed, which can manipulate temperature of the thermionic cathode. The electron emission analysis of thermionic cathode was performed at different temperature ranges where a copper plate (4.7eV) was used as the anode. Based on the results, a total reduction of ~0.36 eV to the work function of the p-type silicon (111) with ~4.84 eV is achieved by the as-synthesized SiC nanowires thermionic cathode using M200SC3 - ~4.48 eV sample. Lastly, the Schottky effect is proven showing an enhancement to the current density of the SiC nanowires thermionic cathode by compromising a small deviation of the work function of ~0.02 eV. These findings prove that the presence of SiC nanostructures on the thermionic cathode has achieved higher current density, 87 nA cm-2 with the presence of applied voltage at 4000 V/cm and 71.8 nA cm-2 at zero field effect, as compared to 14.4 nA cm-2 for the control sample in this TEC study.
Ageing treatment effect on the bending behaviour of nickel-titanium archwires in orthodontic bracket systems
(2024-08-01)
Asad, Munir
Superelastic nickel-titanium (NiTi) archwires have gained popularity as the archwire of choice during the orthodontic alignment and levelling stages because of their capacity to apply light force to the teeth. Generally, orthodontic treatment starts with round archwires and subsequently progresses to rectangular archwires within 4- 6 weeks, ensuring a consistent bending force of approximately 1.0 N. However, commercial NiTi archwires may cause discomfort because of their greater bending force, which exceeds the recommended force for tooth movement. In this study, a novel ageing treatment approach was used to alter the magnitude of the bending force in commercially available superelastic NiTi archwires of various sizes. This study examined three archwires with dimensions of 0.30, 0.40, and 0.40 × 0.56 mm. Subsequently, these archwires were subjected to various ageing temperatures ranging fr om 370 to 550 °C for durations of 15, 30, and 45 min. The archwires underwent thermal analysis, tensile testing, three-point bending testing, and three-bracket bending testing after the ageing treatment. The study used the force deflection curve of aged archwires to evaluate force delivery parameters, and regression models was created to predict the bending force of aged NiTi archwires in orthodontic bracket assemblies. Differential scanning calorimetry (DSC) analysis shows that the ageing treatment effectively alters the thermal transformation temperature of commercial NiTi archwire, with longer durations leading to higher Af temperatures. Furthermore, with ageing treatment, the unloading forces of the commercial NiTi archwire during the three-point and three-bracket tests were reduced to lower magnitudes. The study found that ageing treatment reduced the maximum unloading force of commercial archwire from 2.79 N to 0.21 N for aged rectangular geometry during three-bracket bending, with less impact on round-shaped geometries. The suitable ageing conditions for these archwires were 430–550 °C for 15 min for 0.30 mm, 370–550 °C for 30 min for 0.40 mm, and 400–550 °C for 45 minutes 0.40 × 0.56 mm, respectively. The developed regression models yielded high R-squared values of 0.9677, 0.7207, and 0.7083 and p-values < 0.05 for the loading force, unloading force, and force difference, respectively. The ageing treatment could be employed to improve the force delivery trends of commercial grade NiTi archwire by reducing the magnitude of the force exerted on the teeth during the entire course of orthodontic treatment.
Analysis Of Piston Secondary Motion
(2014-04)
April 2014
In an internal combustion engme, the piston performs secondary motion besides the primary reciprocating motion. The clearance between the piston skirt and cylinder liner allows the piston to move in the lateral direction and rotational motion about the piston pin axis. The piston secondary motion created impact between the piston skirt and the cylinder liner that radiates unwanted engine noise and increases friction loss. A measurement system consists of three laser displacements sensors are developed to capture the instantaneous piston motion and posture directly from the piston assembly under motorized condition. The laser spots aimed at the piston crown with machined profile in order to obtain the rotational and lateral motion of the piston. The instantaneous piston motion showed that the likelihood of contact between the piston skirt and the cylinder liner increases with the occurrence of the piston secondary motion. In addition, a non-linear model of the piston with reciprocating, lateral and rotational degree of freedom is developed to investigate the piston secondary motion and the piston slap induced vibration behavior of the single cylinder engine.
Analysis of tribological and vibration performance of palm olein-based grease containing molybdenum disulphide additive
(2024-07-01)
Nadiah Aqilahwati, Abdullah
The detrimental effects of the mineral-based lubricants and their non-renewable resource has urged the effort in developing a safe and environmentally friendly lubricants. In this study, the effect of additive concentration and particle size was investigated. Three concentrations (0.25, 0.50 and 0.75 wt.%) micro MoS2 was added to the palm olein grease to find the optimum concentration. Based on the optimum concentration, the MoS2 was added in micro and nanoparticles (1-3 µm and 90 nm). The worn surface was analysed by evaluating their coefficient of friction (COF), wear scar diameter (WSD), wear depth, wear volume, wear micrograph image and elemental distribution after a four-ball test. Next, the greases were evaluated by utilising a small-scale spur gear rig. The performance of the palm grease was compared with commercial grease by measuring the gear mass loss, surface characteristics and vibration level. From the four-ball test, palm grease with 0.50 wt.% MoS2 nanoparticles was the optimal grease where it reduced the COF, WSD, wear depth and wear volume for 18.41%, 25.51%, 22.52% and 61.25% compared to grease without additive, respectively. For the gear test, the palm olein grease had 29.04% lower COF but 2.30% higher WSD. The developed palm grease had the lowest roughness difference, mass loss, vibration, and surface damage compared to dry and commercial grease. The findings shows that the developed grease has a good potential to be utilised as a lubricant for a suitable working condition. The performance of the palm olein grease is also on par with the commercial grease.
Analysis of tribological characteristics and performance of palm olein-based grease containing copper nanoparticles
(2024-04-01)
Arif Izzuddin Bin Muhammad
The harmful environmental effect of commercial mineral greases has been raising concerns in the community. Many had reported on the benefit of mineral grease, however, the toxicity and depletion of mineral grease had led to the interest in developing a more sustainable and environmentally friendly grease lubricants. In addition, without nanoparticles such as copper and graphene in grease lubricants, bearings can be exposed to friction and wear faster. Therefore, the aim of this study is to investigate the tribological characteristics and performance of the developed palm olein-based grease with added copper nanoparticles additive. In this study, palm olein based grease was developed using palm olein as base oil and lithium stearate as a thickener. The copper nanoparticle additive was dispersed in the palm olein grease at concentrations of 0.25 and 0.50 wt% and the optimum concentration with the best performance is investigated. The palm olein grease was produced to NLGI 2 grade consistency, which is widely used and suitable for multipurpose applications. This grease is expected to be suitable for a wide range of industries, including agriculture and forestry applications, where the machineries are subjected to environmental exposure. The tribological tests were conducted using a four-ball tribometer to evaluate the wear and friction characteristics of the formulated grease. Further work has been done to investigate the performance of the developed grease by performing an experimental work using a roller bearing test rig. The performance of the palm olein grease was compared with a commercially available mineral grease lubricant. Surface roughness and wear characteristics of the inner race of the roller bearing were analysed periodically and the vibration level was measured. The formulated palm olein grease with copper nanoparticles additive demonstrated enhanced wear resistance, comparable performance to commercial mineral greases during the four-ball friction test with small friction value and wear, and superior performance to commercial mineral grease during the roller bearing test with reduced vibration levels and lower surface degradation. These findings contribute to the knowledge and understanding of palm grease formulations and their potential applications in tribological systems.
Analysis of void formation for no-flow underfill process using numerical simulation and machine learning-based methods
(2022-09-01)
Nashrudin, Muhammad Naqib
The no-flow underfill process has been developed as an alternative to the conventional capillary flow underfill. It offers low cost and lead time production effectively due to the integration of simultaneous reflow of solder interconnect and cure of underfill material. Somehow, no-flow underfill also faces the same reliability issue which is the potential void formation during the process. The research on the void formation issue in no-flow underfill has been found scarce. In addition, the research works on no-flow underfill focused on the experimental method which is costly and very limited to study the root cause of the issue. Therefore, this research presents a numerical simulation study of the no-flow underfill which has the ability to track dynamically the movement of the flow of underfill in real time during the process. This research investigates and predicts the possible void formation of no-flow underfill. Three major parameters were selected to align with industry requirements which are chip placement speed, bump pitches and viscosity of underfill. Subsequently, previous literature of no-flow underfill experiment, industrial no-flow underfill experiment and current scaled-up imitated flip-chip experiment were compared in term of flow and void formation percentage to validate with the current numerical simulation. Overall, the current numerical simulation produced low discrepancy which is less than 15% error among all the experiments and affirmed the capability and accuracy of the numerical simulation model. It was found that the void formation rate increases with the chip placement speed but decreases with the increase in bump pitch. The highest chip placement speed of 14 mm/s produces 4-6% meanwhile, the low chip placement speed (2-5 mm/s) produces around 2-3.5% of void formation. Moreover, several supervised machine learning prediction-based methods such as linear regression, decision forest regression and neural network regression were implemented to train the numerical values and to investigate further the most significant parameter that affects the void formation in the chip. It is observed that linear regression, decision forest regression and neural network regression produced mean absolute errors between 0.1588, 0.176375, and 0.1818, respectively. The neural network regression is the preferred algorithm method of machine learning in the study since it shows the least error with a high R2 value of 0.95159. Based on permutation feature importance, the most significant parameter that affect the formation of void in the no-flow underfill was chip placement speed compared to bump pitches and underfill’s viscosity with a score of 1.7916, 0.2962 and 0.000878, respectively. This research provided engineers in the microelectronic industry with a deep understanding of the void formation and expected to provide an appropriate guide to minimize the failure for the development of no-flow underfill in the future.
Application of Asymptotic Waveform Evaluation (AWE) In Beam and Truss
(2004-02)
Lau, Sun Wah
There is always a misunderstanding that, when a force is applied on a structure (either beam or truss), the maximum deflection or displacement of the material is that shown in steady state. Actually, these structures will deform more than the displacement during the steady state. This is due to the moment caused by the forces as stated in Newton’s second law of motion (F=ma). Because of this unexpected higher magnitude of displacement, many products have failed to achieve its desirable quality. Micro-scale electronic packaging is a very good example. The wire boding equipment causes excessive deflection on electronic package, and damage the tiny component in the package. Earthquake, an undesirable and unexpected disaster, transferring vibration on bridge trusses. Most of the cases, the impulse force from earth fails the structure of bridge trusses. Therefore, dynamic analysis on structure is essential nowadays. Plenty of analysis procedures has been introduced. Among these methods, Finite element method (FEM) has given an accurate result besides of its flexibility. The FEM is a numerical method for solving problems of engineering and mathematical physics (Logan, 2001). However, implementation of Finite Element Method (FEM) in structural and other analysis usually will produce a formulation in space/time domain. This kind of space/time domain formulation leads to a set of ordinary differential equation and have to be solved in the time domain. An implementation of AWE scheme in first and second order ordinary differential equation shows a break through as compared with conventional method. This advanced, powerful and efficient scheme shows excellent result in electronic and thermal analysis (Ooi, 2003; Da-Guang Liu, 1995). In this thesis, AWE is pioneered in beam and truss analysis. Steady state response and dynamic response (before steady state) will be considered.
Attenuation of humming type noise and vibration in vehicle hvac system using a tuneable dynamic vibration absorber
(2023-06-01)
Muhammad Safwan Bin Abdul Aziz
The purpose of this research is to study the effect of a Tuneable Dynamic Vibration Absorber (TDVA) in reducing the humming type noise and vibration that originating from the Heating, Ventilation and Air Conditioning (HVAC) system of a Proton Exora vehicle. In this study, a lab-scale experimental rig of Proton Exora HVAC system was built to represent the system inside the vehicle. On top of that, the study also been conducted on the Proton Exora vehicle itself for the data comparison. The TDVA was designed and tuned according to the natural frequencies of the Air Conditioning (AC) pipe structure obtained from Experimental Modal Analysis (EMA) of both the system and vehicle level with natural frequency values of 148 Hz and 173 Hz respectively. Two TDVA, with the length of 5.53 cm and 4.98 cm were fabricated and applied at both lab scale test rig and vehicle level, respectively. The humming type noise and vibration characteristics of the HVAC components were recorded and compared, with and without the implementation of TDVA. The implementation of TDVA into the system was found to reduce the vibration level of the AC Pipe by 80 % and subsequently reducing the noise and vibration level of the whole HVAC system inside the cabin area by 1.5 dBA. It also been observed that the applied TDVA has an effective frequency range of 100 – 500 Hz for the vehicle level and 75 – 250 Hz for the lab scale test rig.
Bio-based and hybrid based polymer composites for enclosures of memory storage device application
(2022-08-01)
Janakiraman, Vishnu Chandar
A large proportion of consumer electrical and electronic packaging applications were made up of thermoplastics. Casings or enclosures are generally used in circuit boards, and data storage which is made up of plastic to ensure the appliances are mobile, lightweight while being tough and durable and at the same time, the plastics used in these applications are very high and also not biodegradable. This research aims to reduce the usage of plastics in storage applications via two approaches, i.e., bio-based and hybrid-based polymer composites. In this work, pure polymer [polylactic acid (PLA), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), cellulose acetate (CA)] and its bio-based composite ((PLA/Aluminium oxide (Al2O3)/Boron Nitride (BN)), PLA/BN/Graphene tubes (GT), PHBV/Al2O3/BN, PHBV/BN/GT, CA/Al2O3/BN, CA/BN/GT) sheets with different concentration of hybrid filler [(Aluminium oxide (Al2O3)/Boron nitride (BN), BN/Graphene tubes (GT)] were fabricated. Similarly, pure thermoplastics (polyoxymethylene (POM), polypropylene(PP), polycarbonate (PC)) and its hybrid-based composite POM/PHBV/Al2O3/BN, POM/PHBV/BN/GT, PP/cellulose fiber (CF)/Al2O3/BN, PP/CF/BN/GT, PC/basalt fiber (BF)/Al2O3/BN, PC/BF/BN/GT) sheets with different concentration of hybrid fillers were fabricated using internal mixer equipment and compression molding method. The effect of fillers on the structural, optical, thermal, thermophysical, mechanical, surface, electrical properties of the pure polymer and its bio-based and hybrid-based polymer composite sheets were studied, compared, and suggested for electronic packaging applications. XRD results confirm the presence of polymers and fillers (ceramic, carbon, and natural) in the prepared bio-based and hybrid-based composites. The prepared bio-based (PLA/BN/GT, PHBV/BN/GT, CA/BN/GT) and hybrid-based (POM/PHBV/BN/GT, PP/CF/BN/GT, PC/BF/BN/GT) polymer composites exhibit high UV-VIS-NIR absorption, thermal conductivity (0.29 - 0.51 W/mK and 0.35 – 0.53 W/mK), flexural strength (34.2 – 66.4 MPa and 59.1 –74.8 MPa), flexural modulus (1088 – 3239 MPa and 1313 – 3424 MPa), storage modulus (726 – 2130 MPa and 1492 – 3132 MPa), scratch hardness (0.43 – 0.73 GPa and 0.44 – 1.19 GPa), and low CTE (17 - 42.9 µm/m ºC and 38.6 – 114 µm/m ºC), ESD (<10V to <100V and <10V) compared to composites with Al2O3/BN filler and pure polymer that may be due to the high thermal conductivity, mechanical strength and synergetic effect of BN and GT filler. As for dielectric permittivity, Al2O3/BN reinforced composites exhibit favourable dielectric constant (3.02 - 4.74 and 2.72 –3.37) and loss (< 0.02), whereas BN/GT reinforced polymer composites shows higher values at a lower frequency. Like bio-based, hybrid-based polymer composites also follows the same trend in dielectric permittivity. On comparing the bio-based composites, CA/BN/GT polymer composites are suitable for USB products with high storage capacity as per the obtained melting, glass transition temperature, CTE, ESD, mechanical, and scratch performance, whereas PLA/BN/GT and PHBV/BN/GT polymer composites are suitable for USB products with very low storage capacity and can ultimately reduce 98% of plastics. Similarly, the prepared hybrid-based polymer composites (POM/PHBV, PP/CF, PC/BF) with BN/GT filler are suitable for USB, SSD, and HDD products with both low and high capacity as per the obtained thermal, ESD, mechanical, and scratch performance and can ultimately reduce 15-40% of plastics in enclosure applications.
Cascaded cylindrical micro-perforated panel for noise broadband attenuation
(2023-04-01)
Mohamad Izudin Bin Alisah
This research presents an analysis of cascaded cylindrical micro-perforated panel (MPP) for absorbing the sound of a flow system in a circular duct application. This is important for the cases where the noise source comes from multi direction as actual application would not in single direction. Since the typical MPP has limited narrow band attenuation, it is necessary to have a specific MPP to radiate noise from circular direction and broadband attenuation. The aim of this study is to model using simplified transfer matrix method, optimized via genetic algorithm and demonstrate the effectiveness of cascaded cylindrical micro-perforated panel on vacuum cleaner. Cascaded cylindrical MPP is a special class of cylindrical MPP, where two cylindrical MPPs are arranged in series to improve sound attenuation. The manufacturing of MPP primarily involves the machining of micro perforations because the small holes are not readily made using injection moulding due to the complexity of the die, flow control of the molten polymer through the small orifices and dimensional stability, making it unsuitable for mass production. This limitation can be overcome with the use of additive manufacturing (AM) technology based fused deposition method (FDM), where the micro perforations can be designed and manufactured, with relatively larger tolerances. Moreover, parametric studies on basis of perforation diameter, perforation ratio, depth of air cavity on the diameter of the duct and length ratio are carried out. Result shows that the transmission loss performance of cascaded cylindrical MPP can be improved by reducing the perforation diameter and by correct selection of perforation ratio and air cavity depth value. Experimental validation ensures that the manufactured cascaded cylindrical MPP is performed according to design. The application of transfer TMM framework was aligned with similar trend with boundary element method (BEM) and measured result via two-load method measurement. Small shift of the transmission loss peak values attributed to perforations in printed structures that were not perfectly circular in shape. The average Root Mean Square Error (RMSE) obtained was 3.04 dB. A case study is demonstrated here in the design and additive manufacturing of cascaded cylindrical MPP to attenuate peak noise at 1650 Hz. The manufactured cascaded cylindrical MPP is installed on a vacuum cleaner duct, and the measurement of sound power level shows a reduction of 5.2 dB (A).
Characterization of piezoelectric patch and its application to the active vibration suppression for cantilever beam
(2019-08)
Mohd Hafiz Abdul Satar
Piezoelectric is a versatile material where it can be used either as actuator or sensor in many application due to the mechanical and electrical energy conversion. However, the piezoelectric performance is limited by its non-linear characteristics. These characteristics are widely studied but less explored especially involving all the four non-linearity effects (hysteresis, saturation, creep and uncertainty vibration). Thus, this study aims to characterize all four non-linear characteristics of the piezoelectric patch as sensor and actuator and its application to active vibration suppression (AVS) system for a cantilever beam. Then, the piezo is applied on the AVS system to study the performance in three different parameters (frequency independent, controller tuning methods and sine swept). From the study, the result shows that, the hysteresis saturation and uncertainty vibration were significantly found in the actuator and sensor characterizations, while the creep was clearly observed in actuator application. In overall, these four non-linear characteristics were getting worse as the operating frequency and input voltage were higher. At different operating frequencies of AVS, the uncertainty vibration reduction was increased linearly except at 500 Hz. The proportional gain step-up (PGS) was the best tuning method for the AVS system. The frequency dependent study also shown good performance of vibration reduction within the range of 26 Hz to 245 Hz. The main contribution of this study is the characterization of all four piezoelectric non-linear characteristics and its application on the AVS system which shown a significant vibration reduction.
Combustion characterization and optimization of mixture biomass producer gas and methane in a constant volume combustion chamber system for fuel combustion efficiency enchancement
(2023-03-01)
Teh Jun Sheng
Most of the world’s energy requirements are still derived from natural resources. This will result in a catastrophic energy crisis with negative environmental consequences. The increased energy supply will result in greater consumption of non-renewable sources. The production of biomass producer gas (BPG) from biomass gasification has received significant attention for reducing global emissions as an alternative fuel because of the depletion of non-renewable resources. The properties of biomass feedstocks significantly influence combustion characteristics. The objective of this experimental study was to determine the combustion characteristics: flame propagation speed, chamber pressure trace and emissions of BPG at different equivalence ratio to obtain the lower chamber peak pressure and greenhouse gas emissions. Using the direct visualization technique, an optical constant volume combustion chamber (CVCC) was developed to measure combustion characteristics. Liquid petroleum gas (LPG) was used to compare chamber pressure and flame propagation speed in the CVCC calibration. In comparison to wood pellet (WP), coconut husk (CH), and palm kernel shell (PKS), the chamber peak pressure at 𝜙 equal to 1 of CH for the combustion of BPG is the lowest at 20.84 bar. At 𝜙 of 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, and 1.3, the chamber peak pressure of CH was discovered to be around 17.77, 18.12, 18.81, 20.84, 20.39, 17.25, and 16.37 bar. Compared to the other two types of BPG, CH produces the lowest emission of CO2 and CO, at 2.03% and 0.02%, respectively. From the literature review, increasing CH4 content in the fuel can increase the mole fraction of H, O2, and OH radicals and reaction rates in the flame, further accelerating the flame of the mixtures. Therefore, an optimization study is needed to determine the higher performance combustion of BPG with an increase in the composition of methane. The combustion experiment study was optimized with 17 designed experiments, 0.9 to 1.1 equivalence ratio, and the 0 to 0.1 mole fraction of methane fuel. The BPG-methane-air mixture, according to optimization analysis, achieves the fastest flame propagation speed and the lower chamber peak pressure at 𝜙 equal to 1 and a mole fraction of methane fuel of 0.083. Compared to the BPG-air mixture (𝜙 equal to 1), which had a chamber peak pressure of 20.84 bar, the average results of the optimum configuration parameters reveal a lower peak pressure was 18.97 bar. Comparison of the chamber peak pressure between BPG-methane-air mixture and BPG-air mixture varied by approximately 9.39%. In this context, the gross heat release rate (HRR) is observed to be around 94.44 kW, which represents a 20% reduction when compared to CH fuel. However, there is a slight increase in the emissions of CO and CO2, with a rise of 0.01% and 5%, respectively. In conclusion, the optimal mixture of BPG and methane fuel provides the optimum flame propagation speed with lower chamber peak pressure than BPG.
Cutting design for oil palm frond analysis of circular saw
(2024-08-01)
Sun, Qun
This study develop a model to assess energy consumption, cutting force associated with the use of circular saw in the cutting of oil palm fronds. The energy consumption model is formulated based on kinematic equations and a simplified cutting process model, incorporating Ernst and Merchant's force circle. The final cutting power equation considers sawing and clamping, dependent on circular saw geometry, tooth shear angle, disc thickness, feed rate, speed, frond rupture modulus, and friction coefficient between the saw and frond. This model is validated against experimental data (38
Data mining for service industry: branch classification of a malaysia retail bank
(2023-01-01)
Chong Siu Hou
The on-going customers’ behavioural shifts from assessing physical banking services to virtual banking services have made retail banks continually review their physical banking network strategies. Such exercise allows the retail banks to maintain their competitive advantages over their competitors while balancing their business portfolios between online banking service needs, optimizing physical clientele coverage, and minimizing costs in running a physical branch network. The research objective is to develop a suitable classification model in decision-making that can mimic experts’ opinions on retail bank branch operational status using a case study on a Malaysian retail bank. Seventy-four branch attributes were used to build a classification model in which experts’ opinions are included as an attribute to allow the data mining (DM) application to emulate experts’ decision-making. The research methodology involves collecting the experts’ opinion through an expert survey to determine the feasibility of a branch remaining open or closing permanently as part of the bank’s network rationalization strategy. The value obtained from the survey was converted into a variable termed “aggregate closure possibility” in this study and then discretized into target class datasets. Then ten classification models were constructed, including ZeroR, Decision Tree, Random Forest, Naïve Bayes etc. Next, three experiments were conducted. The first experiment examined the effect of hyperparameter tuning on classification accuracy. The second experiment studied the impact of changes in the number of target classes on classifier accuracy and then highlighted the best-performing classifier. When the number of target classes was optimized, the accuracy of classifiers improved drastically, of which, three classifiers (Decision Table, J48, and JRip) were the most accurate classifiers. The third experiment studied the effect of attribute selection and instance reduction in optimizing classification performance. It was observed that the accuracy of most classifiers improved proportionate to the reduction of numbers of attributes and instances where Decision Table, J48, BayesNet, and JRip were the best performing classifiers in the third experiment. The result shows that JRip was the best performing classifier in all three experiments. Attribute selection and instance reduction optimized the classification accuracy in encompassing efficient datasets. The study also showed that the DM application could emulate expert opinion in decision-making in retail banking sector. In conclusion, the study has successfully achieved its research objectives. The study contributes to research knowledge on how DM capabilities could improve management decision-making in a real-world application.
Design and implementation of six rotors unmanned aerial vehicle
(2010-04-01)
Mohamed Aziyen, Mohamed Afique
The control of a helicopter is complex, and includes the interaction of forces and the balancing of them. Although a stable condition can be achieved with sophisticated control system, good mechanical design can reduce the problem of instability of a helicopter. One of the designs is the coaxial types of blade system. Nevertheless, a good control system is still needed since a helicopter control involves many parameters. PIC16F876A microcontroller has been used to measured the input from sensor, do the calculation and control the actuators). In this project, ultrasonic sensor is used to control the height of the helicopter. The force that been produce by the helicopter must be the same to make sure that the helicopter is stable.
Development and documentation on use of completely randomised design
(2010-04-01)
Hamid, Zulkharnain
This project presents the development and documentation of actual engineering examples on the use of the Completely Randomized Design (CRD) in PPKEE. The examples involve a single factor experiment that uses the analysis of variance (ANOVA) technique to analyze the data. Basically the project is to understand the single factor analysis on use of the Completely Randomised Design. The other objective of this project are to search the actual use completely Randomized Design final year students of EE School. After searching, the actual examples of potential use of the Completely Randomised Design are developed based on type of research conducted by the EE students. Minitab is using to analysis the data from the previous final year report. There are a two phase in this project are literature review and develop the examples. The parts reviews and searching of the examples involve the three major courses in school of electrical engineering which is Electrical, Electronic and Mechatronic engineering. From the review of the previous final year report, three examples are developed in the project. The evaluation form was designed to get a feedback from engineering student regarding the examples that have been given. From the analysis of the evaluation form, the performance of the examples were developed are at a good level.
Development and impact of customised serious game system in stable-sitting trunk control exercises among stroke survivors
(2024-08-01)
Tan, Alexander Wai Teng
This study presents a custom Serious Game (SG) system designed for stable sitting trunk exercises. The system incorporates three key features: (1) measurement of the Centre of Pressure (CoP) using a custom force plate, (2) real-time translation of CoP shifts into game avatar control, and (3) recording of CoP trajectories during gameplay. This approach provides an engaging game-based rehabilitation therapy that offers valuable insights into users' functional movements. The study assesses the impact of this SG system on trunk rehabilitation in stroke survivors through a two phase approach. Initially, a within-participant, repeated measures pilot study involved 12 stroke subjects who undertook both conventional trunk exercises (CTE) and SG based trunk exercises (SGTE) in a stable-sitting posture was carried out, aiming to compare the physiological and postural responses. ANOVA results revealed low muscle activity and light-intensity cardiovascular responses across exercises, with game-paced SGTE yielding marginally higher CoP velocity in Anterior-Posterior (AP) and Medio-Lateral (ML) axes compared to CTE (AP: 4.40 ± 1.80 vs. 4.02 ± 1.20 cm/s; ML: 6.40 ± 2.54 vs. 5.42 ± 2.21 cm/s). However, self-paced SGTE had a lesser impact on postural control. Subsequently, a larger cohort of 25 stroke subjects participated in SGTE to explore the relationship between in-game CoP measures and clinical assessment outcomes. Spearman correlation analysis found significant correlations, particularly in the ML axis, with the TIS2.0 score showing a strong association with CoP range (ρ = 0.78; p < 0.001) and mean CoP velocity (ρ = 0.75; p < 0.001). The novelty of this thesis lies in developing a custom SG system specifically designed for trunk rehabilitation in a sitting position for stroke survivors, combining the motivational aspects of games with the clinical relevance of force plate measurements. This study compares the impacts of SGTE on physiological and postural responses with those of CTE in stroke survivors. Additionally, it establishes correlations between in-game CoP measures and clinical assessments among stroke survivors. The findings indicate that the SG system provides impacts comparable to CTE and shows potential as an adjunct to existing rehabilitation protocols and assessment tools for stroke survivors, suggesting further investigation into its utility.
Development and optimization ofmicro gas turbine combustor fueled by refined palm oil
(2024-03-01)
Mohammed Raad, Abdulwahab
Investigations on alternative renewable liquid biofuels to replace petroleum oils have drastically increased in the past decades to mitigate the energy crisis and global warming issues. In Malaysia, the abundance of liquid palm oil waste that can be used directly as fuel or converted into biodiesel (B100) to replace diesel fuel. However, these fuels suffer from high viscosity and lower heating value compared to diesel which presents a major challenge towards achieving clean and complete combustion. This research optimized a new combustion chamber alternative design for micro gas turbine (MGT) applications that can provide clean combustion of low-grade liquid biofuels without the need of fuel preheating or blending with fossil fuels. Chamber design optimization was performed in three stages Design of Experiment (DoE), while combustion and flow hydrodynamics were evaluated using CFD simulation in ANSYS-FLUENT program. Cold-flow spray atomization tests were experimentally performed for refined bleached deodorized palm oil (RBD), B100 and diesel, where spray pictures were analyzed using IC-measure software. RBD oil showed long liquid film extension before breaking down to large droplets resulting in low spray angle <10°, while B100 performed significantly better at lower flow. Increasing the flow increased the spray angle to 21°. The optimum combustion design was then fabricated and tested with Garrett GT-25 turbocharger in single stage MGT test rig. Modifications were then performed to optimize the MGT start-up process with RBD oil. Finally, MGT performance was characterized in the pressure range of 0.2-0.7 bar gauge pressure using RBD oil and palm biodiesel. The performance was compared to diesel as the benchmark fuel. The trend lines of turbine power against compressor pressure using diesel were similar to those of B100 and RBD oil at same pressure range. Minimum CO emission in the range of 132-135 ppm for diesel and B100 were achieved at the higher operating pressures, while RBD oil showed slightly higher value of 207 ppm. NOx emission showed comparable values in the range of 32-39 ppm for all the fuels. Finally, diesel suffered from its higher TIT value that reached 800°C at 0.7 bar compared to 785°C and 762°C for RBD oil and B100 respectively. Chamber efficiency was comparable for all fuel used with low values at low operation pressure and low flame intensity with the range about 85% to 92%. The CFD model was verified with experimental findings at 0.7 bar with low error of 1.6% for TIT, 2.6% for CO and 0.8% for NOx.

Browse

Browsing Pusat Pengajian Kejuruteraan Mekanikal - Tesis by Title

Results Per Page

Sort Options