https://ptsldigital.ukm.my/jspui/handle/123456789/388923 2026-04-26T03:09:18Z https://ptsldigital.ukm.my/jspui/handle/123456789/781722 Title: Genetic algorithms based parameter optimisation using statistical analysis I-kaz for groove defect classification Authors: Nor Afandi Sharif (P83566) Abstract: Accurate signal acquisition is needed due to its implication on the structure integrity status and can lead to major structural failure due to immature signal analysis. The defect on the steel structure is usually associated with a loss of ferromagnetic material on the corrosion region and can be estimated by the magnitude of the Magnetic Flux Leakage (MFL) signal influenced by the depth, width and length of the defect. The challenge for researchers in determining a reliable defect characterisation are, first, the unstructured data with a lot of noise due to stray magnetic field, second, the MFL sensor selection and positioning, third, the parameter optimisation to enhance defect characterisation and reduce latency in postprocessing analysis. As a result, a Genetic Algorithm (GA) combines with the Integrated Kurtosis-based Algorithm for the Znotch filter (I-kazTM) technique for estimating MFL input parameters for defect due to material thinning is proposed. This technique produces a 3D graphic form presenting a degree of data scattering quantified by the coefficient of I-kaz (Z∞) This research aims to study the relationship between sensor acquisition speed and depth of defect using Z∞ using the multilevel signal decomposition technique as an output. The reliability analysis of the experiment is based on statistical verification such as ANOVA and R-square analysis. A complete MFL scanning system is developed using hall sensors and neodymium magnets integrated with a microcontroller as an instrument. The experimental setup comprises 12 Hall effect sensors positioned in an array of 10 cm in width attached on the linear guide for constant scanning speed on the selected setting. The workpiece consists of 10.0 mm, thickness carbon steel SAPH S45C with the designated defects depth of 1.0 mm, 3.0 mm and 6.0 mm to emulate the variability of defect sizes with multiple speed settings of 22.0 mms-1, 44.5 mms-1 and 65.5 mms-1 for each of the thickness. I-kaz multilevel signal decomposition shows the Z∞ increased significantly as the groove and acquisition speed became higher. In total, nine sets of MFL inspection experiments were conducted with various combinations of acquisition speed (20 mms-1 - 70 mms-1), designated depth of defect (1.0 mm to 6.0 mm) and Z∞ as result (0.05 to 0.400). The Response Surface Methodology (RSM) technique is then deployed using historical input from the MFL experiment by inputting speed and depth of defect as input parameters and Z∞ values as an output parameter to generate an equation model of fitness function between the input and output. The fitness function is then used in the GA to estimate the optimum speed and allowable defect depth that can be detected using the developed MFL inspection system by analysing the Z∞ value on each of the experiment runs. The parameter optimisation can be used to produce reliable output data and significant defect characterisation. The result shows the MFL inspection system provide a significant contribution in defect identification and decision-making from an array of hall effect sensor into a single actual value. This system also comes out with a new fitness model using RSM by indicating critical components in MFL inspection using acquisition speed, size of the defect and Z∞ values through historical experimental data. The methodology proves that good resolution of data can be produced with optimised parameters using a single value Z∞ as an output. Description: Fullpage 2022-12-13T00:00:00Z https://ptsldigital.ukm.my/jspui/handle/123456789/781680 Title: The thermal and hydraulic performance of liquid cold plate with novel internal design for electric vehicle battery thermal management Authors: Mohammad Yacoub Khalaf Al Shdaifat (P100974) Abstract: Around the world, there is a significant increase in the number of electric vehicles (EV) on the roads. Among the reasons are due to many countries’ aims to reduce the dependency on the oil as energy source and the environmental aspect, for example the global warming which affect the planet where the transportation represents 30% of it, where the EV is one of the solutions for the global warming. The battery is considered as the main source of power for electric vehicles, but the battery tends to generate significant amount of heat due to an internal resistance during the operation. The generated heat during the charging/discharging processes could lead to overheating in the battery which could end in battery failure. Therefore, dissipating the generated heat in the EV battery becomes essential through thermal management systems to ensure that the battery operates within safe temperature range. The aim of the present experimental study is to introduce a new design of liquid cooling system and to investigate the effective parameters which affect its heat transfer and hydraulic performance. For this purpose, a new liquid cold plate (LCP) with cylindrical fins has been designed and fabricated. There are three focus areas for the research; to study the effectiveness of the shower head in improving the working fluid distribution inside the LCP system and thus improve the heat transfer and temperature uniformity of the battery cells, the effect of using internal perforated LCP with cylindrical fins and the effect of using CUO/WATER NANOFLUID as working fluid in the LCP. All the studies are tested under Reynolds number range between 382 – 1530. To determine the impact of each part used in the present LCP, comparisons are made between the regular and the shower head design, between the internal perforated LCP with cylindrical fins and oblique fins, and between the performance of water and CUO/WATER NANOFLUID as working fluids. Finally, the Design of Experiment program is used for the optimization purpose. The results indicate that the shower head achieved reduction in the surface temperature of the battery cell with significant difference at the low Reynolds numbers. It provides good temperature uniformity compared to the regular inlet that is due to the ability of the shower head to achieve good distribution for the working fluid flowing inside the LCP. For the hydraulic performance, there is no significant difference between the two inlets. There is a clear difference in the surface temperature of the battery cell when using cylindrical and oblique fins. The same observation is found for the temperature uniformity because of its ability to cause better fluid mixing and bigger heat absorption through the working fluid. Hydraulic performance of the internal perforated LCP with cylindrical fins achieved better performance. The impact of using CUO/WATER NANOFLUID to create better battery cooling compared to using water is low, where the differences in the surface temperature of the battery cell is not big while it is almost the same for the temperature uniformity. The hydraulic performance using water gave slightly better performance compared to using the nanofluid. The features of the current novel LCP design are the capability to ensure that the battery cell operates under 41oC and having good temperature uniformity at Reynolds numbers 382-1530 without causing high pumping power consumption penalty. Description: Fullpage 2022-11-23T00:00:00Z https://ptsldigital.ukm.my/jspui/handle/123456789/781616 Title: Angle stability improvement using optimized proportional integral derivative with filter controller Authors: Abdul Waheed Khawaja (P97480) Abstract: Low-frequency oscillations in large power systems may result in system instability under large disturbances. Proper implementation of damping devices is required to dampen oscillations and thus maintain or improve the stability of the power system. Distinct scheme modeling approaches have been used for dampings, such as power system stabilizers, flexible alternating current transmission systems (FACTS), and coordination control. FACTS are commonly used to damp inter-area modes of oscillations. The damping performance of FACTS devices depends on the design of their controllers. The robust design of FACTS controllers requires a suitable objective function and optimization technique to optimize its parameters. Objective function with various formulations has a significant role the in the design of robust damping controllers in power systems. The comparative performance of the objective function application is a critical task in controller design. Its main purpose is to relocate the eigenvalues of a system unstable region into a stable region. This research aims to develop a thyristor-controlled series compensator (TCSC) equipped with a proportional integral derivative with filter (PIDF) controller using a new optimization technique called evolutionary programming sine cosine algorithm (EPSCA) with multi-objective (MO) function. EPSCA is developed by merging evolutionary programming (EP) and sine cosine algorithm (SCA). Meanwhile, the MO function is a combination of three stability indicators: damping ratio, damping factor, and eigenvalues at a certain ratio. EPSCA is designed to optimize TCSC PIDF controller parameters to obtain an optimal solution with a new MO function as an objective function. The TCSC PIDF controller using EPSCA based on MO function was compared with TCSC proportional integral derivative (PID) controller and proportional-integral (PI) controllers. All simulations were accomplished using a linearized mathematical model of the TCSC SMIB system. EPSCA was examined on a single machine infinite bus (SMIB) system under distinct loading situations and compared with three standardized methods, which are SCA, moth flame optimization technique (MFO), and EP. In addition, the TCSC PIDF controller using EPSCA based on MO function was compared with other indicators such as damping ratio (DR) and damping factor (DF) as the objective function. The dynamic performance was validated concerning the damping factor, damping ratio, the eigenvalue’s location in the s-plane, and rotor angle deviation response to demonstrate system stability. MOEPSCA- based PIDF damping controller showed substantial improvements in settling times (7 s) and overshoot (9.4 %) as compared to DR-EPSCA, DF-EPSCA, and PIDFU. MO-EPSCA-based PIDF damping controller showed substantial improvements in settling times (7 s) and overshoot (9.375 %) as compared to TCSC-PID, TCSC-PI, PIDF-U. The EPSCA design design-based damping controller showed significant improvements in settling times (7 s) and overshoot (9.37 %) as compared with SCA, MFO, and EP techniques and un-optimized PIDF-U system. The results showed that the EPSCA based on MO is more effective than the other techniques to tune TCSC PIDF controller parameters and enhance the power system stability by damping oscillations. The suggested method of optimization, which combines a new multiobjective function and damping controller model, validates the robustness of the damping controller's design for the SMIB system and shows that it can be applied to large, interconnected power systems. Description: Fullpage 2022-12-09T00:00:00Z https://ptsldigital.ukm.my/jspui/handle/123456789/780954 Title: Mekanisme penguatan dan sifat mekanik sambungan tikso keluli perkakas d2 menggunakan kaedah peleburan-semula separa langsung Authors: Fadzilah Adnan (P75773) Abstract: Keluli perkakas digunakan secara meluas sebagai acuan tempa, acuan penuangan, blok acuan dan acuan pembetukan dalam pelbagai industri termasuk industri automotif, pembinaan kapal, perkilangan dan jentera kerana sifat kekerasan yang tinggi, kerintangan lelasan dan ubah bentuk. Keluli perkakas sukar dicantumkan atau disambungkan menggunakan kaedah pelakuran lazim kerana suhu kimpalan yang tinggi menghasilkan mikrostruktur dendritik serta pembetukan kecatatan retak kimpalan yang memudaratkan kekuatan sambungan. Oleh itu, matlamat kajian ini ialah menghasilkan sambungan serupa keluli perkakas AISI D2 yang kuat menggunakan kaedah peleburan-semula separa langsung (KPSL) sebagai penyelesaian kepada kesukaran sambungan logam keluli perkakas ini. Dalam kajian ini, julat suhu pemanasan dan pecahan cecair yang sesuai bagi proses sambungan KPSL dikenal pasti. Selain itu, kesan kuasa pemanasan, beban unipaksi, serta rawatan haba pasca sambungan terhadap mikrostruktur dan sifat mekanik sambungan KPSL bagi keluli perkakas D2 telah dikaji. Kalorimetri pengimbasan pembezaan (DSC) dan perisian JMatPro® digunakan untuk mensimulasikan julat suhu dan pecahan cecair serta evolusi fasa terlibat semasa proses sambungan dilakukan. Pemanas aruhan berfrekuensi tinggi digunakan semasa sambungan KPSL dengan kuasa pemanasan yang tinggi serta masa yang singkat iaitu pada kuasa pemanasan 13, 15 dan 17 kW dan suhu pemanasan 1280, 1300 dan 1320 °C. Bagi mendapatkan sambungan yang sempurna, kesan beban unipaksi terhadap sambungan KPSL pada 0, 0.5, 2.5 dan 5 N dikenalpasti. Pencirian sifat mekanik ditentukan dengan menggunakan ujian kerasan dan tegasan-terikan. Perubahan mikrostruktur dan fasa pada sambungan KPSL dikaji menggunakan mikroskop optik, mikroskop imbasan elektron (SEM) yang dilengkapi dengan penganalisis serakan tenaga sinar-X (EDX), dan pembelauan sinar-X (XRD). Keputusan menunjukkan julat suhu yang sesuai bagi pecahan cecair 40, 50 dan 70% adalah masing-masing pada suhu 1280 °C, 1300 °C dan 1320 °C. Sambungan keluli D2 yang dihasilkan adalah bebas retak atau kecacatan. Kekuatan tegangan maksimum tertinggi dicapai adalah pada kuasa pemanasan 17 kW kerana pada kuasa pemanasan yang tinggi dan masa pemanasan yang singkat akan menyebabkan saiz ira menjadi lebih kecil serta kawasan separa pepejal yang lebih tertumpu. Sambungan pada suhu pemanasan 1300 °C serta beban unipaksi 5N menghasilkan mikrostruktur lebih globular berbanding suhu pemanasan yang lain serta menjana kekuatan tegangan maksimum tertinggi melebihi kekuatan bahan logam asas. Mikrostruktur pada kawasan sambungan menunjukkan berlakunya resapan sempadan ira yang ketara apabila beban unipaksi dikenakan semasa proses sambungan yang menyebabkan peningkatan sifat mekanik. Sebaliknya, pada sambungan tanpa kenaan beban unipaksi, lebih banyak karbida eutektik tidak larut di antara ira. Kekuatan tegangan maksimum dan kekerasan selepas rawatan haba pasca kimpalan meningkat kepada 985 MPa dan 860 HV. Ini kerana karbida halus terserak dengan lebih seragam pada matriks dan sempadan ira yang membantu meningkatkan sifat mekanik sambungan. Daripada kajian ini, kekuatan tegangan tertinggi yang dicapai adalah pada KPSL-HT17, dengan nilai 985 MPa berserta kecekapan sambungan 155%. Selain itu, purata nilai kekerasan zon sambungan pada sampel KPSL-HT17 meningkat kepada 890 HV berbanding nilai kekerasan bahan asal adalah 226 HV. Description: Fullpage 2022-10-19T00:00:00Z