Improved gravitational search algorithm for proportional integral derivative controller tuning in process control system

Proportional-Integral-Derivative (PID) controller is one of the most used controllers in the industry due to the reliability and simplicity of its structure. However, despite its simple structure controller, the tuning process of PID controller for nonlinear, high-order and complex plant is difficult and faces lots of challenges. Conventional method such as Ziegler-Nichols are still being used for PID tuning process despite its lack of tuning accuracy. Nowadays researchers around the world shift their attention from conventional method to optimisation-based methods. For the last five years, optimisation techniques become one of the most popular methods used for tuning process of PID controller. Optimisation techniques such as Genetic Algorithm (GA), Particle Swarm Optimisation (PSO) as well as Gravitational Search Algorithm (GSA) are widely used for the PID controller application. Despite the effectiveness of GSA for PID controller tuning process compared to the GA and PSO technique, there is still a room for improvement of GSA performance for PID controller tuning process. This research represents the additional characters in GSA to enhance the PID controller parameter tuning performance which are Linear Weight Summation (LWS) and alpha parameter range tuning. Performance of optimisation-based PID controllers are measured based on the transient response performance specification (i.e. rise time, settling time, and percentage overshoot). By implementing these two approaches, results show that Improved Gravitational Search Algorithm (IGSA) based PID controller produced 20% to 30% faster rise and settling time and 25% to 35% smaller percentage overshoot compared to GA-PID and PSO-PID. For real implementation analysis, IGSA based PID controller also produced faster settling time and lower percentage overshoot than other optimisation-based PID controller. A good controller viewed as a controller that produced a stable dynamic system. Therefore, by producing a good transient response, IGSA based PID controller is able to provide a stable dynamic system performance compared to other controllers

Biodiversiti dan pemuliharaan terumbu karang di tiga buah pulau, Melaka

Di negeri Melaka terdapat lapan belas pulau yang direkodkan oleh Perbadanan Muzium Negeri Melaka (PERZIM). Sebahagian daripada pulau ini berperanan sebagai pulau pelancongan, pulau yang dibangunkan ada juga pulau yang tidak didiami. Walaubagaimanapun, terdapat tiga buah pulau yang direkodkan mempunyai terumbu karang istimewa yang masih berada dalam keadaan yang baik. Sehubungan itu, pihak Institut Penyelidikan Perikanan Batu Maung Pulau Pinang (AkuaTAR) telah menjalankan kajian biodiversiti terumbu karang di sekitar perairan Pulau Dodol, Pulau Serimbun dan Pulau Undan menggunakan kaedah selaman skuba selain turut menjalankan pemuliharaan ke atas terumbu karang yang telah dikenalpasti di perairan selat Melaka itu. Objektif kajian ini adalah untuk merekodkan jenis komuniti bentuk seperti karang hidup selain mengenalpasti spesies terumbu karang yang terdapat di tiga buah pulau di negeri Melaka iaitu Pulau Undan, Pulau Dodol dan Pulau Serimbun. Kajian ini juga mengimplementasikan metod pemerhatian dengan menjalankan kajian lapangan di pulau yang terlibat dengan melakukan selaman skuba. Hasil dan perbincangan mendapati, ketiga-tiga pulau ini mempunyai kawasan perairan yang sangat bersih, tidak didiami serta memiliki pelbagai biodiversiti batu karang yang terdiri daripada terumbu karang lembut dan terumbu karang keras. Kajian ini juga mendapati ketiga-tiga pulau di negeri ini mempunyai terumbu karang yang terbesar di perairan selat Melaka

Kedah Tua sebagai pelabuhan kuno perdagangan antarabangsa antara abad ke-2M sehingga 13M: lambang ketamadunan bangsa Melayu

Kedah Tua merupakan sebuah kerajaan Melayu lama yang wujud sejak zaman protosejarah lagi. Penemuan pelbagai artifak dan candi oleh pengkaji arkeologi antaranya tapak ritual, tapak peleburan besi dan pelabuhan kuno membuktikan masyarakat Kedah Tua mempunyai peradaban yang tinggi. Justeru, kajian ini telah menarik perhatian pengkaji untuk menfokuskan faktor kemunculan Kedah Tua sebagai pelabuhan kuno perdagangan antarabangsa antara abad ke-2 masihi sehingga abad ke-13 masihi. Periodisasi sepanjang 1100 tahun ini menyaksikan era kecemerlangan kerajaan Kedah Tua khususnya dari aspek perdagangan dengan tamadun luar antaranya China, India dan Arab. Kajian konseptual ini menggunakan kaedah kualitatif dengan mengaplikasikan metod sejarah. Tinjauan literatur terhadap kajian-kajian arkeologi dianalisis dan ditulis berdasarkan intrepretasi sejarah. Hasil kajian ini mendapati kedudukan geografi Kedah Tua, sistem transaksi perdagangan yang cekap, naungan kekuasaan empayar dan hasil komoditi tempatan menjadi pemacu kepada faktor kemunculan Kedah Tua sebagai pelabuhan kuno perdagangan antarabangsa antara abad ke-2 masihi sehingga abad ke-13 masihi. Implikasi penyelidikan ini meningkatkan jatidiri bangsa Melayu rentetan pembuktian kajian bahawa masyarakat Kedah Tua sebagai tamadun bangsa yang hebat

Natural fiber-reinforced hybrid polymer nanocomposites: effect of fiber mixing and nanoclay on physical, mechanical, and biodegradable properties

Combining two kinds of fibers is a potential way to improve the essential properties of natural fiber-reinforced hybrid polymer composites. Biocomposites produced from natural resources are experiencing an increase in interest due to their high demand in the market for manufacturing, in addition to environmental and sustainability issues. In this study, natural fiber-reinforced hybrid polymer nanocomposites were prepared from coir fiber, wood fiber, polypropylene, and montmorillonite nanoclay using a hot press technique. The effects of fiber mixing and montmorillonite on their physico-mechanical and biodegradable properties were subsequently investigated. Before being used, both the wood and the coir fibers were alkali-treated to reduce their hydrophilicity. The mechanical properties of the fabricated composites were measured using a universal tensile testing machine and found to be enhanced after fiber mixing and nanoclay incorporation. Fourier transform infrared spectra indicated that the characteristic peaks of the composites shifted after fiber mixing. A new peak around 470 cm-1 was observed in the case of the nanocomposites, which confirmed the interaction between the fiber, polymer, and montmorillonite (MMT). Scanning electron microscopic analysis revealed that MMT strongly improved the adhesion and compatibility between the fiber and polymer matrix. The combining of fibers improved the biodegradability and water absorption properties, while MMT addition had the reverse effect on the same properties of the composites

Gravitational search algorithm optimization for PID controller tuning in waste-water treatment process

This paper presents a new approach of optimization technique in the controller parameter tuning for waste-water treatment process (WWTP) application. In the case study of WWTP, PID controller is used to control substrate (S) and dissolved oxygen (DO) concentration level. Too many parameters that need to be controlled make the system becomes complicated. Gravitational Search Algorithm (GSA) is used as the main method for PID controller tuning process. GSA is based on Newton's Law of Gravity and mass interaction. In this algorithm, the searcher agents survey the masses that interact with each other using law of gravity and law of motion. For WWTP system, the activated sludge reactor is used and this system is multi-input multi-output (MIMO) process. MATLAB is used as the platform to perform the simulation, where this optimization is compared to other established optimization method such as the Particle Swarm Optimization (PSO) to determine whether GSA has better features compared to PSO or vice-versa. Based on this case-study, the results show that transient response of GSA-PID was 20%-30% better compared to transient response of the PSO-PID controlle

Natural Fiber-Reinforced Hybrid Polymer Nanocomposites: Effect of Fiber Mixing and Nanoclay on Physical, Mechanical, and Biodegradable Properties

Combining two kinds of fibers is a potential way to improve the essential properties of natural fiber-reinforced hybrid polymer composites. Biocomposites produced from natural resources are experiencing an increase in interest due to their high demand in the market for manufacturing, in addition to environmental and sustainability issues. In this study, natural fiber-reinforced hybrid polymer nanocomposites were prepared from coir fiber, wood fiber, polypropylene, and montmorillonite nanoclay using a hot press technique. The effects of fiber mixing and montmorillonite on their physico-mechanical and biodegradable properties were subsequently investigated. Before being used, both the wood and the coir fibers were alkali-treated to reduce their hydrophilicity. The mechanical properties of the fabricated composites were measured using a universal tensile testing machine and found to be enhanced after fiber mixing and nanoclay incorporation. Fourier transform infrared spectra indicated that the characteristic peaks of the composites shifted after fiber mixing. A new peak around 470 cm-1 was observed in the case of the nanocomposites, which confirmed the interaction between the fiber, polymer, and montmorillonite (MMT). Scanning electron microscopic analysis revealed that MMT strongly improved the adhesion and compatibility between the fiber and polymer matrix. The combining of fibers improved the biodegradability and water absorption properties, while MMT addition had the reverse effect on the same properties of the composites