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Al Mamun, Md. Abdullah,Islam, Md. Shafiqul Korea Institute of Construction Engineering and Ma 2017 Journal of construction engineering and project ma Vol.7 No.1
This paper represents the experimental investigation of chloride penetration into plain concretes and reinforced concretes. The main objective of this work is to study the main influencing parameters affecting corrosion of steel in concrete. Plain cement concrete and reinforced cement concrete with different water-cement ratios and different cover depth were subjected to ponding test. Ponding of specimens were done for different periods into 10% NaCl solution. Depth of penetration of chloride solution into specimens was measured after ponding. Specimens were crushed and reinforcements were washed using $HNO_3$ solution and weight loss due to corrosion was calculated accordingly. There was a linear relationship between depth of penetration and water-cement ratio. It was also observed that, corrosion of reinforcing steel increases with chloride ponding period and with water-cement ratio. Corrosion of steel in concrete can be minimized by providing good quality concrete and sufficient concrete cover over the reinforcing bars. Water-cement ratio has to be low enough to slow down the penetration of chloride salts into concrete.
Discrete time Adaptive Controller for Suppression of Resonance in Hard Disk Drive Servo System
Md. Arifur Rahman,Abdullah Al Mamun,Kui Yao 제어·로봇·시스템학회 2015 International Journal of Control, Automation, and Vol.13 No.5
Mechanical resonant modes of the actuator severely impede the efforts in achieving high precision in head positioning servo system of hard disk drives (HDD). Hence it is important that these modes be properly compensated. The conventional approach is to use a notch filter in cascade with the nominal controller, which works well if the resonant frequencies are known and do not vary during operation. However, in reality, frequency and damping ratio of the resonant modes vary in mass-produced systems. They also get changed over time due to wear and tear. As a result, auto-tuning or adaptation of the notch filters is required to maintain the performance at the same level. In this paper, a discrete time adaptive controller is presented in a simple and yet efficient way to suppress the effects of resonant modes. Effectiveness of the proposed compensator is demonstrated through simulation and experiments by implementing the compensator for a Voice Coil Motor (VCM) actuator used in HDD.
Mamun, Abdullah-Al,Kabir, Md. Humayain,Kader, Mohammed Abdul,Hossain, Mohammed Kamal Institute of Forest Science 2021 Journal of Forest Science Vol.37 No.1
This study was conducted at Sitakunda coastal afforestation range, comprised of four beats- Bansbaria, Bakkhali, Baterkhil and Bogachattar, in Chittagong. Afforestation effects on soil physicochemical properties in comparison to adjacent barren land were analysed. In the study area, an area of 3277.33 ha was planted with Sonneratia apetala, Avecinnia officinalis, Excoecaria agallocha, Bruguiera sexangula, Ceriops decandra from 1968 to 2011. We found positive soil physicochemical changes in plantations in comparison to adjacent barren land. Soil bulk density of plantation was lower than the adjacent barren land. Soil pH and soil salinity were significantly higher in barren land whereas soil organic matter, organic carbon, nitrogen, phosphorus, potassium of plantations were higher in afforested land. Soil texture ranged from clay loam to sandy loam in different depth of these two types of land. However, this study concludes that there is clear evidence that afforestation has positive impacts on all soil properties in different location and soil depths in the study area.
Md. Reazuddin Repon,M. Tauhidul Islam,Md. Abdullah Al Mamun 한국의류학회 2017 Fashion and Textiles Vol.4 No.1
Variety and durability of color are presumed as key constrains of natural dyes. So, this study attempts to investigate the effect of metallic mordants on the color fastness properties of ecologically dyed cotton fabric using banana floral stem sap. Color difference was measured in terms of hue (ΔH*), chroma (ΔL*) and value (ΔC*) difference. Metal ions in residual mordanting bath, dyeing wastewater and level of trace metals in the finished fabric surface were accessed to justify the environmental safety and speculate the health risk respectively. Pre-mordanted specimens were dyed at 100 °C for 60 min. Optical properties of extracted sap were observed by UV visible spectroscopy. Dye fixation with fiber was determined by FTIR-ATR spectra. Atomic absorption spectroscopy was employed to determine the trace metals in finished fabric. Effect of metallic mordants were calculated in terms of color fastness to wash, water, perspiration, rubbing and light for estimating the color durability. Except light fastness property almost all color fastness values were 4/5, i.e. very good. Light fastness properties were improved for mordanting action with metallic salts. The level of trace metals in finished fabric were within the safe zone.
Mamun Abdullah Al,Rahman Muhammed Forruq,Aysha Akhtar,Md. Wahidul Alam,Mohammad Nurul Azim Sikder,Alan Warren,Henglong Xu 한국해양과학기술원 2018 Ocean science journal Vol.53 No.4
To investigate the seasonal heterogeneity of the periphytic ciliate communities, a 1-year baseline survey was conducted in the Karnaphuli River estuary, northern Bay of Bengal, Bangladesh. A total of 54 ciliate species were recorded, including seven common and 14 dominant species. Maximum species number was in autumn whereas maximum abundance was in winter; the minimum for both occurred in summer. Multivariate analyses, i.e., canonical analysis of principal coordinates (CAP) and principal co-ordinates analysis (PCoA), revealed a clear seasonal heterogeneity of community structure and environmental variables. Multivariate correlation analysis (RELATE) demonstrated that the community structure of the periphytic ciliate communities was significantly correlated with environmental variables, and best matching analysis (BIOENV) indicated that heterogeneity of community patterns was mainly driven by water temperature, pH, dissolved oxygen, total dissolved solids and nutrients. Species richness and diversity peaked in autumn whereas species evenness peaked in summer. These results suggest that environmental conditions shape periphytic ciliate community structure, which is a potentially useful bio-indicator of estuarine water quality.
MUHIBBULLAH, Md.,MAMUN, Abdullah Al,AFROZ, Rafia Korea Distribution Science Association 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.2
This paper describes the intent of learners to acquire university education, the basis for selecting study courses, the means to assess the quality of higher education, what the challenges faced by the learners are, as well as suggestions for improvement. The design and system thinking approach has been adapted to address the well-being issues of B40 young people in Bangladesh, through understanding their need, followed by building conceptual business models using modeling tools, i.e., Business Model Canvas (BMC) and Value Proposition Canvas (VPC) model. The main objective of this paper is to investigate the contribution and the role of a Malaysian University to solve problems of quality of higher education in Bangladesh and what initiatives should be taken to overcome this problem. This paper offers a validated conceptual Malaysian University of the Future (UotF) business model with the focus on international community engagement programs to help Bangladeshi students to acquire knowledge, abilities, skills, and values toward developing a harmonious and sustainable society. The contribution of this paper is the presentation of a conceptual, validated business model in both BMC and VPC formats. This conceptual business model can further be applied to civic engagement operations by other universities.
Evaluation of Bamboo Reinforcements in Structural Concrete Member
Siddika, Ayesha,Al Mamun, Md. Abdullah,Siddique, Md. Abu Bakar Korea Institute of Construction Engineering and Ma 2017 Journal of construction engineering and project ma Vol.7 No.4
This study is based on the use and performance of bamboo reinforcements in construction of low-cost structures. This study investigated the physical and mechanical properties of bamboo reinforcements. Bamboo reinforced concrete beam specimens were tested with different reinforcement ratios and observed the load capacity, deflection and failure patterns. It was observed that, flexural strength of bamboo reinforced column is sufficient higher than plain cement concrete and comparable to steel reinforced concrete beams. Bamboo reinforced concrete columns with different reinforcement ratio also tested and observed the ultimate compressive strength and failure pattern. It found, all columns failed in a similar pattern due to crushing of concrete. According to cost analysis, bamboo reinforced beams and columns with moderate reinforcement ratio showed the best strength-cost ratio among plain cement concrete and steel reinforced concrete.
Ecotourism Carrying Capacity and the Potentiality of the Safari Park of Bangladesh
Masum, Kazi Mohammad,Al Mamun, Abdullah,Rahman, Zahed Mohammad Malekur,Rahman, Md. Motlubur,Newaz, Md. Shah,Redowan, Mohammad Institute of Forest Science 2013 Journal of Forest Science Vol.29 No.4
The study was undertaken to assess the tourist's carrying capacity and to explore ecotourism potential of Bangabandhu Sheikh Mujib Safari Park, the only safari park of Bangladesh. Carrying capacity was assessed both from physical and social aspect. On the other hand, 250 visitors were interviewed with semi structured questionnaire for ecotourism prospect evaluation along with some secondary data. The total daily-allowed visit was 17,300 with rotation coefficient of 3.46. Maximum daily average numbers of tourists were relatively below the physical carrying capacity of the Park (5,000). The social carrying capacity was 4.38 persons per day. As there are different categories of visitors, their choice of encounters and number of expected encounters also varied. Each year, the total tourist's number varied significantly ($p{\leq}0.05$). That proved the safari park had immense tourist prospect. 85 percent visitors were from lower and middle class family as entrance fees and other fees inside were very cheap in relation to other private amusement place. The ecological perspective of the park will remain unaltered if the carrying capacities of the area are followed with sustainability. Therefore, it is the proper time for taking appropriate decision.