Model predictive control for current balancing in a four-phase buck converter

Multiphase buck topology offers smaller ripple current and lower component ratings. This, however, compromises unbalanced output current between each phase of an inductor which leads to over-current and inductor saturation issues. Often when discussing the linear control schemes, it involves the use of superposition theorem to understand the system’s response. However, the limitation of superposition theorem in this application is that it assumes the circuit to be completely linear. For components with nonlinear behaviour such as power switches and diodes, the analytical results may not be accurate resulting to unexpected behaviour as the algorithm is implemented on a real system. Hence, the use of a more advanced control scheme is necessary to improve a system with a non-linear characteristic. This paper proposes a current limit control (CLC) consists of MPC for inner loop control and PID for outer loop control for phase current balancing in a four-phase buck converter. The controller is designed to achieve balanced current for each phase with acceptable response time. The proposed system is designed using MATLAB/Simulink simulation software and verified by a laboratory prototype with a TMS320F28335 as the main controller. Simulation and experimental results are provided to validate the system performance

Effect of water to cement ratio and replacement percentage of recycled concrete aggregate on the concrete strength

Fine Recycled Concrete Aggregate (FRCA) is one of the construction waste can be recycled. It can be the aggregate to replace the natural aggregate in concrete since we know the physical properties of materials are hard and strong. Demand for sand in the concrete production has been increased which become the problems in the concrete industry. This work deals with the effect of concrete incorporating with FRCA as partial replacement of sand. The percentage of natural sand replaced by the FRCA was 0%, 15%, 20%, 25%, 30%, 45% and 60%. Other than that, water cement ratio was manipulated variable started form 0.40, 0.45, 0.50, 0.55 and 0.60. In short, 20% replacement was the most suitable interaction of FRCA in the concrete occur that contribute to increasing in compressive strength. The porosity properties of FRCA been neutralized on that replacement percentage by the present of optimum filler effect generated form the very fine FRCA particle during the mixing process. Meanwhile, 0.50 water cement ratio was optimum condition for cement hydration process using FRCA as partial sand replacement

Interfacial reaction between SAC305 lead–free solders and ENImAg surface finish and bare copper

Different surface finishes on printed circuit board strongly influence the formation of intermetallic compounds (IMCs), and solder joint reliability. In this paper the effect of two different substrates namely electroless nickel/immersion silver (ENImAg) and bare copper on interfacial reaction when exposed to a reflow soldering process are presented. The result revealed that the black line nickel disappeared on the electroless nickel/immersion silver surface finish after the plating process. Subsequently, the intermetallic compound formed on electroless nickel/immersion silver surface finish are (Cu,Ni)6Sn5, and (Ni,Cu)3Sn4 with a chuck-shape, rode-type, and needle-shape after reflow soldering. Meanwhile, only Cu6Sn5 layer is found on bare copper with a spherical-shape. The results also indicated that different surface finishes are affected by the growth of intermetallic formation and shear strength, where tin-3.0silver-copper0.5/copper (SAC305/Cu) produced a thicker intermetallic layer, larger grain size, and less shear strength compared with tin-3.0silver-copper0.5/electroless nickel immersion silver (SAC305/ENImAg) surface finish

Travelling Islam - Madrasa Graduates from India and Pakistan in the Malay Archipelago

The phenomenon of travelling religious traditions has attracted the attention of various scholars, but a differentiated understanding of its nature and impact is still lacking. This essay addresses the transnational and transregional impact of educational traditions in Islam in the South-South direction. It traces the impact of two education networks based in South Asia on Islamic learning in South East Asia. Both the modernist institutions of the International Islamic University and the conservative Deoband schools together with the affiliated Tablighi Jama'at have made significant headway in Malaysia, Indonesia, Singapore and beyond. The case study argues that the impact is far from unidirectional and more multifaceted than often assumed. It is largely shaped by the social and cultural experience of local society and driven by its needs, rather than by a transnational agenda

Green corridors for liveable and walkable city: A case of Kuala Lumpur

The concept of sustainability embraces the conservation of the environment, cultural preservation, economic stability and overcoming of social problems. To ensure urban sustainability, one of the crucial factors is the environmental health, in which the environment should be kept in the best condition in developing countries thereby leading to reduction of environmental pollution. Green corridors in cities are one such way to ensure that the green areas are being used optimally. Such studies do exist in Malaysia but there is no established and published implementation. There is a need to analyse and study the current problems of the existing green corridors plans. This paper helps to visualise all the six suggested routes of the green corridors that had been made in Kuala Lumpur city. It discusses the opportunities and limitations of the plans as well as ways to improve for a successful implementation of green corridors in Kuala Lumpur

Identification of suitable trees for urban parks and roadsides in Iskandar Malaysia

Urban trees provide a number of benefits, mainly for environment, community, and economy, but can also be harmful to property and human lives. Urban trees planted at roadsides with low endurance rate and unhealthiness increase the risk of tree fracture and fall which is hazardous to motorists and pedestrians. Overhanging limbs, on the other hand, can obscure streetlights, signs and traffic signals and affect road users’ vision in vicinity. These situations contribute to the cumulative maintenance burden to the local authority. This makes the study of maintenance level and suitable location for urban tree planting important. An appropriate maintenance and location can be suggested for assuring a healthy, safe, resilient and long-term survival of urban trees. Urban tree field data from two local authorities in Iskandar Malaysia region (located in the southern part of Peninsular Malaysia), Johor Bahru City Council, and Pasir Gudang Municipal Council, were obtained to achieve the objective of this study. Survey based on questionnaire was conducted to gain detailed information about the maintenance level of existing trees and their suitable locations in the cities from the professionals including urban planners, landscape architects, and certified arborists. By applying a simple scoring method to the data obtained from professionals, suitable locations for existing trees in the two cities were determined. The scores range between 0 and 300 and the highest value means less maintenance is required by the trees. Results show that Mimosup elengi tree species (Sapotaceae family) has the highest score of 300 followed by Cinnamomum verum (297) and Hopea odorata (283). Khaya senegalensis, on the other hand, with 245 score value was found to require high levels of maintenance. The results also indicate that maintenance level and suitable location for planting vary and depending on the features of the tree species. Strongest trees or limbs tend to cause less problems thus require less maintenance. Trees found in the nature (forest) including Mimosup elengi and Cinnamomum verum are usually more resilient and can tolerate a wide range of conditions and locations. This study can help reducing the risk of tree fracture and fall, prolong the life of trees, and reduce the burden of maintenance for local authorities and decision makers by providing insights to the maintenance level and suitable locations for planting and to make better management plans for urban forestry in Malaysia in the future

Persepsi Nelayan Melayu Terhadap Program Perikanan Laut dalam: Satu Kajian Kes di Mersing, Johor Darul Takzim

Tumpuan kajian ialah mengenai persepsi terhadap perikanan laut dalam (PLD) di kalangan nelayan Melayu di Mersing, Johor. Objektif umum kajian ialah untuk mengenal pasti faktor-faktor terpilih yang menentukan persepsi mereka. Objektif khusus kajian ialah untuk melihat samaada wujud pertalian antara 15 pembolehubah bebas iaitu umur, pendidikan, bilangan tanggungan, pengalaman kerja, kemahiran kerja, keahlian dalam persatuan, pendapatan perikanan, keupayaan bot, jarak operasi, tempoh operasi, ganjaran kerja, kemudahan Kerajaan, pengalaman buruk di laut, ketakutan di laut dan ikatan sosial dengan pembolehubah sandar iaitu persepsi mereka terhadap PLD. Kaedah statistik yang digunakan dalam analisis ialah korelasi Pearson 'r' dan regresi berganda. Kekerapan, peratusan dan tabulasi silang digunakan bagi tujuan deskriptif ke atas latar belakang responden dan situasi luaran yang terlibat. Analisis korelasi menunjukkan bahawa enam daripada 15 pembolehubah bebas mempunyai pertalian bererti dengan persepsi terhadap PLD. Lima dari padanya iaitu umur, pengalaman kerja, kemahiran kerja, ganjaran kerja dan penerimaan kemudahan Kera jaan mempunyai pertalian positif dengan persepsi terhadap PLD. Satu pembolehubah lain iaitu ikatan sosial pula menun jukkan pertalian yang negatif. Analisis regresi menun jukkan bahawa hanya lima pembolehubah bebas penting bagi menentukan persepsi terhadap PLD. Antara lima pembolehubah tersebut, jarak operasi merupakan yang terpenting dan diikuti oleh ikatan sosial, umur, ganjaran kerja dan keupayaan bot. Secara keseluruhannya, persepsi responden terhadap kerjaya PLD adalah menggalakkan. Lebih kurang satu pertiga daripada mereka berminat untuk menyertai atau kekal dalam kerjaya tersebut. Kurang satu perempat pula tidak berminat langsung dan kurang berminat menyertainya. Hampir separuh pula tidak dapat membuat pilihan. Faktor latar belakang diri yang terpenting yang menentukan persepsi mereka adalah jarak operasi, umur dan keupayaan bot. Faktor situasi luaran terpenting pula adalah ikatan sosial dan ganjaran kerja

Blackspot analysis of road traffic crashes in Surabaya - Manyar Toll Road, East Java

Traffic crashes are one of the problems that cannot be prevented, especially on toll roads. Knowing the crash element, including crash number, type, factor, and fatality, could lead the investigation to set crash solving and prevention by finding the blackspot point. Surabaya-Manyar toll roads were reported as crash-prone locations, with 149 crashes from 2014-2018. This research concerns the impact on a specific period obtained by PT. Margabumi Matrajaya was ranging from 2014-2018 at Surabaya-Manyar toll road. The objectives aim to analyze the crash element using submitted data from PT. Margabumi Matrajaya to find the blackspot at each line. The collected data were the primary data from field observation and documentation and secondary data, consisting of crash data, road length, time of the crash, what types of vehicles were involved in the crash, and wound victim data. The locations of crash-prone points (Blackspots) on the Surabaya - Manyar Toll road are as follows: The locations of crash-prone points (Blackspots) on the Surabaya Toll road - Manyar line mostly occurred at Km 9 + 925 - 16 + 400 mostly in 2018, on the Romokalisari - Kebomas section, and for Manyar - Surabaya line, occurred at Km 3 + 500 - 0 + 000 mostly in 2016, on the Tandes - Dupak section. Therefore, to decrease the crash number in Surabaya - Manyar toll road, PT. Margabumi Matrajaya should add traffic sign as blackspot area, speed trap, warning sign like slippery road ahead warning, crossroad, and merging traffic

Utilization of sawdust ash as cement replacement for the concrete production: a review

Cement is the main materials for the construction and it is very expensive. Considering the growing demand of cement, the researchers are probing towards the new cement replacement materials. To achieve the sustainable development, it is imperative to use supplementary cementing materials in the field of concrete engineering. Currently, numerous research has been conducted on the utilization of sawdust ash as a cement replacement in the production of green building material and an alternative means of wood waste minimization. The result of this research work has indicated that sawdust ash has a good potential to be utilized as replacement of ordinary Portland cement for the production of concrete. The aim of this review work is to summarize previous research studies on utilization of sawdust ash as a cement replacement. Hence, this review paper will provide the significant idea and valuable information for the fellow researchers working for the composite cement materials, supplementary cementing materials in the field of concrete technology and it is the considerable verdict that more research is deserved to be carried out on the development of high-strength concrete incorporating sawdust ash as a cement replacement

Auditing scholarly journals published in Malaysia and assessing their visibility

The problem with the identification of Malaysian scholarly journals lies in the lack of a current and complete listing of journals published in Malaysia. As a result, librarians are deprived of a tool that can be used for journal selection and identification of gaps in their serials collection. This study describes the audit carried out on scholarly journals, with the objectives (a) to trace and characterized scholarly journal titles published in Malaysia, and (b) to determine their visibility in international and national indexing databases. A total of 464 titles were traced and their yearly trends, publisher and publishing characteristics, bibliometrics and indexation in national, international and subject-based indexes were described