Convergence Study for Rock Unconfined Compression Test Using Discrete Element Method

Mesh convergence is a vital issue that needs to be addressed in a numerical model. This study investigated the effects of mesh element number on the Discrete Element Method (DEM) to granite rock response under compression loading. This study used the 3D finite-element code LS-DYNA to model the Unconfined Compression Test (UCT) numerical simulation. Models with five different mesh types were conducted for convergence mesh, namely normal mesh, fine mesh, super fine mesh, coarse mesh, and super coarse mesh. The mesh convergence of rock media has been conducted using DEM and steel plates simulated using the Finite Element Method (FEM). The DEM-FEM numerical analysis is compared with the results obtained from the experimental test. The best mesh was obtained as the simulation could reproduce the stress-strain curve trends, the failure behaviour and compression strength observed in the experimental test. The normal mesh was selected as the best mesh type in this study based on the comparisons that have been made. This study shows that the DEM-FEM numerical simulation can represent granite rock and can be used for further study based on mesh convergence

Alor Setar sebagai pusat komersial sebelum kemasukan British, 1735-1909

Artikel ini akan meneliti perkembangan Alor Setar sebagai sebuah pusat komersial dalam tempoh 1735-1909. Dalam konteks ini, perkembangan Alor Setar akan ditinjau dari sudut apakah bentuk aktiviti-aktiviti komersial yang dijalankan serta apakah faktor pencetus kepada perkembangan bandar Alor Setar yang lebih pesat. Kajian ini menggunakan kaedah kualitatif yang melibatkan pengumpulan dan analisis data daripada sumber-sumber primer yang diperoleh daripada Arkib Negara Malaysia seperti Surat Sultan Muhammad Jiwa kepada Francis Light, Peringatan Raja-raja Kedah, Surat Menyurat Sultan Abdul Hamid dan CO 716, Kedah/Perlis Sessional Papers, 1905-1937. Hasil kajian mendapati bahawa bermula pada tahun 1735, apabila Alor Setar mula berfungsi sebagai pusat pentadbiran negeri, bandar tersebut dilihat semakin mendapat tumpuan penduduk sama ada dari dalam mahupun luar Kedah. Dalam tempoh ini, berlaku aktiviti perdagangan yang pesat di antara Alor Setar dan pedagang daripada luar seperti Pulau Pinang, India dan China. Antara komoditi yang diperdagangkan termasuklah bekalan makanan seperti beras, haiwan ternakan dan kayu kayan. Hasil perdagangan ini menyumbang pendapatan yang besar kepada negeri Kedah. Di samping itu, aktiviti komersial di Alor Setar dirancakan lagi dengan kewujudan emporium perniagaan yang menempatkan kedai menjual pelbagai jenis barangan seperti kedai pajak gadai, gedung menjual pakaian dan peralatan kegunaan harian. Kemunculan Alor Setar sebagai sebuah pusat komersial yang pesat ini disumbang oleh beberapa faktor seperti kecekapan pentadbiran di bawah kepimpinan yang berwibawa, kawalan keselamatan yang efisien dan sistem perhubungan dan pengangkutan yang canggih, sistem kawalan kesihatan yang mapan dan kewujudan pelabuhan bandar yang menjadi daya tarikan terpenting kepada golongan pedagang

Sistem ‘Indus-Train’: medium pemantauan dan penilaian pelajar semasa latihan industri / Amminudin Ab Latif … [et al.]

Latihan industri merupakan satu kursus wajib dalam program Diploma Kejuruteraan Awam, UiTM Pahang bagi memberi pendedahan amalan kejuruteraan yang sebenar kepada para pelajar dan untuk memenuhi keperluan kelayakan akreditasi 'Engineering Technician Accreditation Council'(ETAC). Namun begitu, proses penilaian dan pemantauan ke atas pelajar yang menjalani latihan industri adalah tidak sistematik kerana buku log tidak lengkap, rubrik pemarkahan tidak spesifik, penilaian oleh pensyarahyang bukan dalam bidang kepakarannya, tiada dan tidak berkala lawatan dan pemeriksaan ke tapak oleh penyelia fakulti, tiada pemantauan aktiviti harian oleh penyelia fakulti serta laporan akhir tidak berformat. Dalam era globalisasi kini, kaedah ini seharusnya perlu ditambahbaik bagi memastikan latihan industri pelajar lebih sistematik, berdaya saing, mengurangkan kos pengurusan serta mencapai kelestarian dalam penilaian latihan industri. Oleh itu, sistem 'Indus-Train' telah dibangunkan oleh Kumpulan Inovatifdan Kreatif(KIK) (CivTEX), FKA UiTM Pahang bagi membantu jabatan menyelesaikan masalah-masalah yang berbangkit berkaitan dengan pemantauan dan penilaian latihan industri. Impakpositif utamayang diperoleh adalahpeningkatan pencapaianpelajar dalam hasil kursus (CO) secara spesifiknya COl iaitu peningkatan 13.2%. Disamping itu,sistem ini juga menjimatkan masa dan mengurangkan kos. Nilai tambah sistem ini adalah sijil latihan industri dapat dicetak pada akhir semester dan melalui kod bar sijil ini, ia dapat diimbas menggunakan aplikasi khas telefon pintar untuk melihat segala laporan aktiviti-aktiviti pelajar ketika menjalani latihan industri. Sijil ini boleh dijadikan salah satu dokumen bagi tujuan permohonan pekerjaan

Empirical strenqth envelope for shale

Effectively, strength envelope describes behavior of a rock body when subjected to common stresses in construction, namely compressive, tri-axial and tensile. This study is aimed at investigating the strength envelope for shale, a sedimentary rock obtained from dam project site in Baram, Sarawak. Series of triaxial compression tests were carried out to obtain the strength envelope for the rock samples. For verification of failure criterion, uniaxial compression and Brazilain tests were also conducted on the rock samples. Results from the related tests were analysed using RocData software to obtain the strength envelope. Subsequently, Mohr-Coulomb and Hoek-Brown failure criterion are used to determine failure envelop for the rock samples. Based on the failure envelopes and the related strengths (i.e. compressive and tensile strength), suitability of both approach, in defining strength envelope for shale, is verified. The study shows that for highly laminated sedimentary rock like shale, Hoek-Brown criterion gave a more representative failure behaviour. The failure envelope clearly shown all the strength limits when the rock subjected to triaxial, uniaxial and tensile stress, which is not observed in Mohr-Coulomb. Hoek-Brown criterion is more superior for describing rock body as mass strength rather than material strength

Assessment of compressive strength of peat soil with sawdust and Rice Husk Ash (RHA) with hydrated lime as additive

Construction activities on peat soils are found to be extremely difficult as the soil is profound as soft soil and has low shear strength and high moisture content. Due to alternating swelling and shrinkage nature, it causes serious damage to the structure above it. This happens due to repetition of drying and wetting of soil. Stabilization of soil is commonly applied to improve the mechanical properties of soil prior to soil engineering works. This soil improvement method is advantageous and effective one by using waste materials. Waste in our country is divided in various types and it includes domestic wastes, industrial wasters, agricultural wastes etc. Because of difficulties to diminish these wastes without affect to environment and surroundings, it can be used as a stabilizing agent in the soil. Therefore, this experimental study carried out to evaluate the effect of Rice Husk Ash (RHA) and sawdust on engineering properties of the peat soil. The properties such as compaction and unconfined compressive strength are determined separately with sawdust and added of RHA in peat soil at a variety of percentages (2.5%, 5% etc.) in addition small amount of constant rate of lime with 2% of the dry soil weight. By obtaining the results, it can deduce a promising and improving result in stabilizing the soil with sawdust and Rice Husk Ash in both economic and strength capacity. This will not only solve the waste disposal problem but also enhance the strength characteristics of soil significantly

Assessment of compressive strength of peat soil with sawdust and Rice Husk Ash (RHA) with hydrated lime as additive

Construction activities on peat soils are found to be extremely difficult as the soil is profound as soft soil and has low shear strength and high moisture content. Due to alternating swelling and shrinkage nature, it causes serious damage to the structure above it. This happens due to repetition of drying and wetting of soil. Stabilization of soil is commonly applied to improve the mechanical properties of soil prior to soil engineering works. This soil improvement method is advantageous and effective one by using waste materials. Waste in our country is divided in various types and it includes domestic wastes, industrial wasters, agricultural wastes etc. Because of difficulties to diminish these wastes without affect to environment and surroundings, it can be used as a stabilizing agent in the soil. Therefore, this experimental study carried out to evaluate the effect of Rice Husk Ash (RHA) and sawdust on engineering properties of the peat soil. The properties such as compaction and unconfined compressive strength are determined separately with sawdust and added of RHA in peat soil at a variety of percentages (2.5%, 5% etc.) in addition small amount of constant rate of lime with 2% of the dry soil weight. By obtaining the results, it can deduce a promising and improving result in stabilizing the soil with sawdust and Rice Husk Ash in both economic and strength capacity. This will not only solve the waste disposal problem but also enhance the strength characteristics of soil significantly

Empirical Model and Validation of Bar Formation in Sand Bed Channel

Both present experimental and previous historical data were used to develop the empirical model. Generally, the aim of this study to establish an empirical model of bar formation from the present experimental data and selected historical data. Statistical techniques using Multiple Linear Regression Analysis were employed for empirical model development and the selection of bar formation parameters were done based on the works of previous investigators. Validation of the newly developed empirical model was done by using a different set of historical data from selected laboratory studies. Model development involved selection of parameters through review of established models, dimensional analysis to check on the homogeneity of the model and statistical analysis. Derived empirical model has been validated using a different set of data from previous studies. Analysis confirmed that the empirical model derived using linear regression technique depicts the highest discrepancy ratio accuracy of 90% with Dds${D \over {{d_s}}}$ and BD${B \over D}$ as the most significant parameters that promote bar height formation

Empirical Model and Validation of Bar Formation in Sand Bed Channel

Both present experimental and previous historical data were used to develop the empirical model. Generally, the aim of this study to establish an empirical model of bar formation from the present experimental data and selected historical data. Statistical techniques using Multiple Linear Regression Analysis were employed for empirical model development and the selection of bar formation parameters were done based on the works of previous investigators. Validation of the newly developed empirical model was done by using a different set of historical data from selected laboratory studies. Model development involved selection of parameters through review of established models, dimensional analysis to check on the homogeneity of the model and statistical analysis. Derived empirical model has been validated using a different set of data from previous studies. Analysis confirmed that the empirical model derived using linear regression technique depicts the highest discrepancy ratio accuracy of 90% with ${D \over {{d_s}}}$ and ${B \over D}$ as the most significant parameters that promote bar height formation

Non-Traditional Security Issues in Southeast Asia during COVID-19: Implications and Mitigation Strategies by ASEAN

Since the end of the Cold War in the 1990s, problems of security have become increasingly important. The contemporary notion is that the security of the state is no longer threatened just by conflict, but also by other circumstances and challenges that continue to endanger the well-being of citizens and the state. The objective of this concept paper is to examine ASEAN’s response towards selected non-traditional security issues during the COVID-19 pandemic, such as infectious disease (COVID-19), regular and irregular migration, food security, cyber security, and the implications faced by ASEAN in such matters. The library research method was used by the author in this article. Several keyword search strings were used, including “nontraditional security issues”, “COVID-19 in Southeast Asia”, and “mitigation measures by ASEAN”. Thus, this study offers new insights and suggestions by focusing on the implications and prospects of ASEAN solutions to NTS concerns caused by COVID-19 as the virus spread throughout Southeast Asia. The findings also indicate that regional cooperation is an integral feature of coordinated efforts by governments and non-state entities, such as non-governmental organizations (NGOs), in combating these security concerns. The blueprint for NTS also can be suggested to help further understand these issues

Effectiveness and tolerability of repetitive transcranial magnetic stimulation for preventive treatment of episodic migraine: a single-centre, randomised, double-blind, sham-controlled phase 2 trial (Magnet-EM)

Background: This is a phase II randomised, double-blind, sham-controlled trial to evaluate the effectiveness and tolerability of repetitive transcranial magnetic stimulation for preventive treatment of episodic migraine amongst migraine subjects. Methods: Subjects age 18 to 60 years will undergo a baseline evaluation to establish the diagnosis of migraine based on the International Classification of Headache Disorder 3rd Edition (ICHD-3). Those who fulfil the ICHD-3 criteria for episodic migraine and compliant to the headache diary during a month run-in period will be enrolled. A total of 76 subjects will be randomised to receive either transcranial magnetic stimulation or sham stimulation for 5 sessions within 2 weeks duration. Follow-up sessions will be conducted monthly for three consecutive months. Prior to treatment, subjects will be required to fill up questionnaires and undergo few procedures such as electroencephalography, transcranial Doppler ultrasound and biochemical analysis for serum serotonin, serum calcitonin gene-related peptide and serum beta-endorphin. These procedures will be repeated at month 3 after receiving the last treatment. The primary outcome measure of this study is the difference in mean monthly migraine days at baseline and at months 1, 2 and 3 after treatment sessions. Discussion: Following evidence from previous studies showing restoration of dorsolateral prefrontal cortex (DLPFC) activation to almost normal level, the rTMS intervention will target left DLPFC in this study. An intermediate duration of treatment sessions is selected for this study. It is set to five treatment sessions given within 2 weeks duration