https://ptsldigital.ukm.my/jspui/handle/123456789/388953 2026-04-15T11:12:10Z https://ptsldigital.ukm.my/jspui/handle/123456789/777863 Title: Development of miniaturized metamaterial absorbers for electromagnetic radiation absorption in the microwave and near infrared regions Authors: Afsar, Md. Salah Uddin (P108627) Abstract: The exotic characteristics of electromagnetic metamaterial absorber made it the focal point of wireless electromagnetic communication system. Many metamaterial absorbers already been proposed but the limitations are that most of them are bulky in size, poor performance, using multi-layers, and above all no scientific explanations were described regarding the structural parameters related to the metamaterial absorber (MMA) properties. The main aim of the thesis is to design, characterization and giving vivid scientific explanations of electromagnetic wave absorption mechanism for perfect MMA in the microwave regime and near infrared (NIR) of solar spectrum. It is also shown to relate the structural parameters with the resonance frequencies by designing some new metamaterial based absorbers. Hereafter, designing a miniaturized single layered perfect metamaterial absorber in the microwave and near infrared frequency band have become new research work for scientific community. Three new compact design structures were developed and analysed in this research to absorb the electromagnetic wave in the microwave regime and these three designs were implemented to absorb solar radiation in the near infrared (NIR) regime by using rescaling method. The proposed MMAs were numerically analysed by using Finite Integration Technique (FIT) based high frequency electromagnetic simulator (CST) microwave studio. The two important methods, Nicolson-Ross-Weir (NRW) and Fresnel method were used to characterize the MMAs extracting the material properties such as permittivity, permeability and refractive index. After that the electromagnetic behaviour of microwave absorbers were authenticated by LC tank circuit and experimentally measured by a vector network analyser. The first design was comprised with four symmetric swastika shaped with a circular split ring that yielded three resonance peaks at 3.03, 5.83 and 7.23 GHz with the absorbance of 99.84%, 99.03% and 98.26%, respectively. It covered S-, and C-band of satellite applications. The second design consisted of two orbits like circular rings with a metal disc on the orbit and circular metal disc in the centre of two orbits which yielded three absorption peaks at 3.02, 5.71 and 8.36 GHz with the absorbance of 99.86%, 97.58% and 97.46%, respectively. The third one was a cart wheel shaped MMA that yielded quadruple absorbance peaks at 2.88, 5.42, 7.62 and 10.24 GHz with the absorbance 99.73%, 93.57%, 99.68% and 99.78%, respectively. In addition, these three perfect MMAs were rescaled to design nano MMA structures to absorb solar energy. Maximum rates of absorbance numerically analysed by the CST microwave studio were 97.32%, 97.62% and 99.74% at 378, 234.80 and 199.30 THz for the swastika shaped, solar system shaped and cart-wheel shaped, respectively. These analyses propose the practical applications of satellite communications, radar cross-section, stealth and coating technologies, defense and security purposes for next generation EM communication devices. 2024-02-01T00:00:00Z https://ptsldigital.ukm.my/jspui/handle/123456789/777862 Title: Development of coding based metasurface absorber for radar cross section reduction and electromagnetic interference shielding Authors: Hossain, Md Bellal (P109529) Abstract: Radar cross section (RCS) reduction and electromagnetic interference (EMI) shielding are crucial for enhancing the stealth and electromagnetic compatibility of various systems, including military platforms, by minimizing radar detection and mitigating electromagnetic interference. Coding-based metasurface absorbers (CMA) show promise in RCS reduction and EMI shielding applications, countering the limitations faced by conventional metasurface absorbers in achieving significant reductions due to inherent design constraints. This research aims to develop a coding technique to enhance the capabilities of metasurface absorbers in achieving high RCS reduction and shielding effectiveness. The simulation process extensively employed Computer Simulation Technology (CST) Microwave Studio, a high-frequency electromagnetic simulator based on the Finite Integration Technique. The coding element comprises of a triple circular ring resonator designed on Flame Retardant 4 substrate which generates 1-bit coding scheme (‘0’ and ‘1’ element) with a reflection phase difference of 1800, and 2-bit coding utilizes four elements (‘00’, ‘01’, ‘10’, and ‘11’) with a phase difference of 900, respectively. Binary Particle Swarm Optimization (BPSO) algorithm with array theory is applied to choose the best location for unit cells in the subarray in order to achieve high shielding effectiveness and RCS reduction. For this reason, the better results were obtained from this research. Firstly, three novel conventional metasurface absorbers, including one with a double E shape, another with double elliptical-based resonators and a third with triple circular rings, were designed and analysed for the dual purposes of reducing RCS and offering EMI shielding. Secondly, a 1-bit CMA were effectively designed and analysed for RCS reduction and EMI shielding applications. The CMA demonstrates excellent capabilities, including an absorption levels exceeding 80% at different resonance frequency within the frequency range of 9.04 GHz to 14.7 GHz, strong shielding effectiveness, and a significant reduction of -10 dBsm in RCS between 7.5 GHz and 15.5 GHz. Finally, 2-bit CMA pattern using same unit cell design as 1-bit utilizing the variable dimension of outer circular ring reveal promising results. Simulation results show that the optimized 2-bit CMA pattern presents -10 dBsm RCS reduction across a wide frequency band of 7.5 to 17.5 GHz. The CMA pattern demonstrates high shielding effectiveness by maintaining near unity absorption performance regardless of polarization and incident angle insensitiveness. The findings indicate that 2-bit CMA pattern provides greater flexibility compared to the 1-bit pattern, for instance, the 2D and 3D scattering pattern of 2-bit CMA at 11.9 GHz demonstrate superior results compared to the 1- bit CMA. Additionally, the monostatic RCS and absorption results also indicate better performance with the 2-bit CMA compared to the 1-bit CMA. Finally, the effectiveness of the CMA pattern was verified through experimental investigation to evaluate its capability in absorption performance and shielding against EMI. Coding based metasurface absorbers have a significant potential for applications involving RCS reduction and the EMI shielding because they have the ability to manipulate electromagnetic waves to achieve various functionalities. 2024-01-20T00:00:00Z https://ptsldigital.ukm.my/jspui/handle/123456789/776958 Title: Kesejahteraan hidup warga emas Temuan: Kajian kes di bandar dan pinggir bandar Selangor Authors: Nor Hafizah Mohd Fizer (P77474) Abstract: Pembangunan memberi kesan kepada peningkatan salah satu daripada elemen kesejahteraan hidup iaitu jangka hayat. Justeru, di negara ini akan berlaku pertambahan warga emas yang mana ia seiring dengan situasi semasa. Namun demikian, peningkatan jangka hayat masih perlahan dalam kalangan warga emas Orang Asli. Secara relatifnya jangka hayat dan populasi mereka lebih rendah berbanding masyarakat arus perdana. Pembangunan yang disediakan di negara ini memberi kesan kepada warga emas secara umumnya tetapi bagi warga emas Orang Asli situasi mereka adalah berbeza. Oleh itu, kesejahteraan hidup warga emas Orang Asli dipersoal kerana jangka hayat yang rendah. Justeru penelitian kajian ini terhadap warga emas Temuan di Selangor, mempunyai empat objektif utama iaitu mengenalpasti status kesejahteraan hidup warga emas; mengkaji hubungan struktur keluarga dan sokongan sosial terhadap kesejahteraan hidup; menganalisis strategi lokal yang dapat meningkatkan kesejahteraan hidup; dan mencadangkan langkah intervensi yang bersesuaian ke arah kesejahteraan hidup warga emas Temuan. Kajian dijalankan di bandar dan pinggir bandar, dalam daerah Petaling dan Kuala Langat di Selangor. Pendekatan kajian adalah secara mod campuran kuantitatif dan kualitatif, iaitu sebanyak lapan buah kampung terlibat merangkumi 261 warga emas Temuan menjadi responden kepada soal selidik; 45 warga emas Temuan menjadi informan utama dan agensi kerajaan telah ditemubual secara bersemuka. Hasil dapatan kajian menunjukkan nilai kumulatif indeks kesejahteraan hidup warga emas Temuan di bandar dan pinggir bandar berada di tahap sederhana. Dari sudut domain, hanya ekonomi sahaja menunjukkan nilai indeks berada di tahap rendah di bandar dan pinggir bandar. Petempatan di bandar, kawasan Rancangan Penempatan Semula dan Rancangan Pengumpulan Semula jelas menunjukkan cabaran yang dihadapi oleh warga emas dalam mengharungi pembangunan semasa. Domain budaya dan psikologi adalah signifikan kedua-duanya di bandar dan pinggir bandar, dan perlu diambilkira sebagai elemen utama dalam kesejahteraan hidup selain daripada yang terdapat dalam Pelan Tindakan Dasar Warga Emas Malaysia (DWEN). Selain itu, sokongan sosial juga memberi kesan kepada kesejahteraan hidup warga emas. Manakala dari sudut strategi lokal menunjukkan mereka masih lagi aktif dengan aktiviti sosial bersama keluarga dan komuniti. Bagi meningkatkan lagi kesejahteraan hidup, intervensi berkaitan sosial, ekonomi, persekitaran dan kesihatan perlu diperhalusi semula dengan mengambilkira keperluan warga emas Temuan. Secara keseluruhan, warga emas Temuan tidak menerima kesan ketara dalam perubahan arus pemodenan yang merubah peranan dan status warga emas. 2024-05-27T00:00:00Z https://ptsldigital.ukm.my/jspui/handle/123456789/776956 Title: Impak transformasi digital dalam pengurusan strategik dan kesejahteraan pekerja di klinik dan hospital kerajaan ke arah kelestarian revolusi industri ke-empat (4IR) di Malaysia Authors: Mohd Firdaus Mohd Arif (P103823) Abstract: Transformasi digital disorot sejak bermulanya revolusi perindustrian pada abad ke-18 apabila revolusi ini dikesan di Britain melalui penggunaan enjin pada mesin yang menjadi pemangkin kepada teknologi dan inovasi yang berkembang mengikut fasa-fasa tertentu. Walaubagaimanapun, transformasi digital mungkin menimbulkan kekangan pada kalangan pekerja apabila melaksanakannya, sama ada dari aspek pengurusan mahupun kesejahteraan pekerja. Laporan Ketua Audit Negara Persekutuan Tahun 2018 mendedahkan bahawa Kementerian Kesihatan Malaysia (KKM) menghadapi kekangan/halangan dalam mengurus dan menyediakan perkhidmatan meliputi aktiviti pengurusan pencapaian kewangan, beban kerja pekerja, pengurusan kemudahan kecemasan, dan keupayaan teknologi maklumat. Maka, kajian ini mengkaji pelaksanaan, penggunaan dan kemajuan transformasi digital dalam pengurusan strategik di klinik dan hospital kerajaan, dan juga kesannya terhadap kesejahteraan kakitangan di tempat berkenaan. Kajian ini meliputi 6 hospital dan 6 klinik kesihatan menggunakan kaedah mod campuran. Untuk analisis kuantitatif, soal selidik yang mengandungi 49 item telah dibangunkan, dan seterusnya dijawab oleh 405 responden yang menggunakan sistem digital dan 385 responden yang tidak menggunakan sistem digital di tempat kerja. Bagi analisis kualitatif, seramai 8 responden telah ditemubual melalui 47 soalan di mana 6 responden adalah daripada kalangan pengguna sistem. Ketekalan sela keyakinan pada skala Cronbach alpha bagi soal-selidik kuantitatif adalah 0.877. Dalam aspek kesejahteraan, kajian mendapati transformasi digital memberi impak positif terhadap kesejahteraan psikologi kakitangan perkhidmatan kesihatan pada lima daripada enam dimensi yang diuji dimana dimensi mahir persekitaran, perkembangan kendiri dan hubungan positif memberi pengaruh yang amat besar. Manakala kesejahteraan psikososial menunjukkan kesejahteraan pada kelima-lima elemen yang diuji. Elemen sosio-teknikal melalui penilaian empirikal menunjukkan perkaitan signifikan yang tinggi pada elemen infrastuktur dan elemen budaya bagi penggunaan sistem digital. Penelitian mendapati medium transformasi digital yang dilaksanakan di klinik dan hospital kerajaan mempunyai kelebihan kompetitif untuk dikembangkan ke fasiliti-fasiliti lain di seluruh negara. Penerimaan transformasi digital didapati berbeza mengikut fasiliti dimana ianya lebih diterima di hospital. Analisa transformasi digital sebagai pemangkin kelestarian mendapati bahawa fasiliti memainkan peranan penting iaitu di mana transformasi digital itu dilaksanakan; faktor demografi seperti jawatan dan tempoh perkhidmatan mempunyai kolerasi negatif yang signifikan (nilai-p < 0.05) terhadap elemen teknologi, ekonomi, alam sekitar dan politik. Dapatan kajian yang dibentangkan telah melalui proses-proses analisis faktor dan hubungkaitnya iaitu Ukuran Kecukupan Persampelan melalui Ujian Kaiser-Meyer- Olkin (KMO) dan Bartlett's Sphericity, Ujian Kotak Kesamaan Matriks Kovarian yang juga dikenali Ujian Box-M dan matriks kolerasi faktor. Selain menentusah data adalah taburan normal, nilai signifikan yang diperolehi seperti communalities, matriks komponen dan eigen telah digunakan sebagai justifikasi Ujian-t, Ujian korelasi dan Ujian Manova terhadap faktor-faktor yang dikaji. Kajian dengan konsep positivist ini mengelakkan penyetaraan agar dapatan tidak bersifat deduktif. Analisis kualitatif didalami melalui Penerangan Reka Bentuk Berjujukan menggunakan kaedah interpretasi praktikal penilaian kluster tematik. Kajian membangunkan pengukuran kesejahteraan implementasi digital melalui kerangka yang dinamakan SISK agar 2024-06-21T00:00:00Z