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Search Results: 1 - 10 of 1484 matches for " Rashid Mahbub "
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CFD Analysis for Optimum Thermal Design of Carbon Nanotube Based Micro-Channel Heatsink
Farhad Ismail,A. I. Rashid,M. Mahbub
Engineering Journal , 2011, DOI: 10.4186/ej.2011.15.4.11
Abstract: Carbon nanotube (CNT) is considered as an ideal material for thermal management in electronic packaging because of its extraordinary high thermal conductivity. Fabricated onto a silicon substrate to form micro-channels, the CNT based cooling fins show high heat dissipation efficiency. A series of 2D and 3D CFD simulations have been carried out for CNT based micro-channel cooling architectures based on one and two dimensional fin array in this paper using COMSOL 4.0a software. Micro-channels are generally regarded as an effective method for the heat transfer in electronic products. The influence of various fluids, micro-fin structures, fluid velocity and heating powers on cooling effects have been simulated and compared in this study. Steady-state thermal stress analyses for the forced convection heat transfer are also performed to determine maximum allowable stress and deflections for the different types of cooling assembly.
Development and reliability testing of a self-report instrument to measure the office layout as a correlate of occupational sitting
Duncan Mitch J,Rashid Mahbub,Vandelanotte Corneel,Cutumisu Nicoleta
International Journal of Behavioral Nutrition and Physical Activity , 2013, DOI: 10.1186/1479-5868-10-16
Abstract: Background Spatial configurations of office environments assessed by Space Syntax methodologies are related to employee movement patterns. These methods require analysis of floors plans which are not readily available in large population-based studies or otherwise unavailable. Therefore a self-report instrument to assess spatial configurations of office environments using four scales was developed. Methods The scales are: local connectivity (16 items), overall connectivity (11 items), visibility of co-workers (10 items), and proximity of co-workers (5 items). A panel cohort (N = 1154) completed an online survey, only data from individuals employed in office-based occupations (n = 307) were used to assess scale measurement properties. To assess test-retest reliability a separate sample of 37 office-based workers completed the survey on two occasions 7.7 (±3.2) days apart. Redundant scale items were eliminated using factor analysis; Chronbach’s α was used to evaluate internal consistency and test re-test reliability (retest-ICC). ANOVA was employed to examine differences between office types (Private, Shared, Open) as a measure of construct validity. Generalized Linear Models were used to examine relationships between spatial configuration scales and the duration of and frequency of breaks in occupational sitting. Results The number of items on all scales were reduced, Chronbach’s α and ICCs indicated good scale internal consistency and test re-test reliability: local connectivity (5 items; α = 0.70; retest-ICC = 0.84), overall connectivity (6 items; α = 0.86; retest-ICC = 0.87), visibility of co-workers (4 items; α = 0.78; retest-ICC = 0.86), and proximity of co-workers (3 items; α = 0.85; retest-ICC = 0.70). Significant (p ≤ 0.001) differences, in theoretically expected directions, were observed for all scales between office types, except overall connectivity. Significant associations were observed between all scales and occupational sitting behaviour (p ≤ 0.05). Conclusion All scales have good measurement properties indicating the instrument may be a useful alternative to Space Syntax to examine environmental correlates of occupational sitting in population surveys.
Amelioration of Salinity Stress in Maize Seed Germination and Seedling Growth Attributes through Seed Priming  [PDF]
Lucky Akter, Oli Ahmed Fakir, Md. Khairul Alam, Mahbub Ul Islam, Priyanka Chakraborti, Md. Jahangir Alam, Md. Harunur Rashid, Mahfuza Begum, Md. Abdul Kader
Open Journal of Soil Science (OJSS) , 2018, DOI: 10.4236/ojss.2018.85011
Abstract: Germination of seeds and growth of seedling respond to seed priming as priming can guard the damage of salinity stress. A study conducted in the net house of the Department of Agronomy, BAU, Mymensingh during the period from November 2012 to April 2013 investigated the ameliorative effect of seed priming on seed germination and seedling attributes of maize under various salinity stress conditions. The experiment consisted of five seed priming and four salinity levels (NaCl) and laid out in a Completely Randomized Design (CRD) with three replications. Seed germination and seedling attributes of maize varied due to salinity stress and priming. The highest seed germination (95.7%) was recorded when no stress was imposed under hydropriming (48 hours). The germination of seeds performed even well (92.3%) when treated with hydropriming (48 hours) and NaCl@0.25 dS·m-1 which was followed by hydropriming (24 hours) under no salinity imposed and NaCl@0.25 dS·m-1 salinity. Hydropriming for 48 hours without salt stress performed the best on number of leaves seedling-1 (8), shoot length (28.2 cm), root length (14.5 cm), fresh weight (100.8 g) and dry weight of seedling (50.3 g). The germination and seedling growth parameters were reduced with the increase in salinity levels irrespective of priming while all seed priming treatments showed ameliorative effects. However, reduction in seed germination and seedling attributes were minimal with hydropriming for 48 hours. The results revealed that priming of maize seeds could be used for amelioration of salinity stress and hydropriming for 48 hours appeared as the best seed priming treatment.
Neonatal mortality: a scenario in a tertiary level hospital of a developing country
Mamunur A.K.M. Rashid,Habibur C.H. Rasul,Mahbub S. Hafiz
Pediatric Reports , 2010, DOI: 10.4081/pr.2010.e9
Abstract: This study was designed to observe the overall neonatal mortality and pattern of neonatal death in a developing country. The factors related to neonatal mortality are also analyzed. This retrospective study was carried out in all pediatric patients in a tertiary level hospital of a developing country in the year 2008. Total neonatal (0-28 days) and non-neonatal (after 28 days-12 years) admissions and death records were analyzed. There were a total of 3,194 admissions in the year 2008. Neonatal and non-neonatal admissions numbered 942 and 2,252, respectively. There were a total of 146 (15.5%) neonatal deaths among neonatal admissions and 114 (5.06%) non-neonatal deaths among non-neonatal admissions. There were 87 (59.59%) preterm related deaths and 98 (67.12%) deaths due to Low Birth Weight (LBW). There were 102 (70%) deaths among neonates who had no antenatal follow-up. Mother’s age was under 20 years in 80 (55%) cases of neonatal death. The number of neonatal deaths is high in developing countries. Preterm with Low Birth Weight (LBW) is the major cause of mortality. Regular antenatal care and social discouragement of early marriage can greatly reduce neonatal death. Skilled and trained nursing care is necessary for the survival of the preterm and Low Birth Weight (LBW) baby in the hospitals of developing countries.
A Radio Based Intelligent Railway Grade Crossing System to Avoid Collision
Sheikh Shanawaz Mostafa,Md. Mahbub Hossian,Khondker Jahid Reza,Gazi Maniur Rashid
International Journal of Computer Science Issues , 2010,
Abstract: Railway grade crossing is become the major headache for the transportation system. This paper describes an intelligent railway crossing control system for multiple tracks that features a controller which receives messages from incoming and outgoing trains by sensors. These messages contain detail information including the direction and identity of a train. Depending on those messages the controller device decides whenever the railroad crossing gate will close or open.
A Radio Based Intelligent Railway Grade Crossing System to Avoid Collision
Sheikh Shanawaz Mostafa,Md. Mahbub Hossian,Khondker Jahid Reza,Gazi Maniur Rashid
Computer Science , 2011,
Abstract: Railway grade crossing is become the major headache for the transportation system. This paper describes an intelligent railway crossing control system for multiple tracks that features a controller which receives messages from incoming and outgoing trains by sensors. These messages contain detail information including the direction and identity of a train. Depending on those messages the controller device decides whenever the railroad crossing gate will close or open.
A Probabilistic Delay Model for Bidirectional VANETs in City Environments
Md. Mamunur Rashid Akand,Mir Tafseer Nayeem,Md. Rokon Uz Zaman Sumon,Muhammad Mahbub Alam
Computer Science , 2014,
Abstract: Routing in VANETs (Vehicular Ad hoc NETworks) is a challenging task due to large network sizes, rapidly changing topology and frequent network disconnections. State-of-the-art routing protocols tried to address these specific problems especially in city environments (vehicles constrained by road geometry, signal transmissions blocked by obstacles, degree of congestion in roads etc). It was noticed that in city scenarios codirectional roads consist of a collection of disconnected clusters because of traffic control strategies (e.g., RSU (Road Side Units), stop signs and traffic lights). In this paper, we propose an intervehicle ad-hoc routing metric called EFD (Expected Forwarding Delay) based on the vehicular traffic statistics (e.g., densities and velocities) collected on-the-fly. We derive an analytical expression for the expected size of a cluster in co-directional traffic. In case of disconnection between two co-directional clusters the opposite directional clusters are used as a bridge to propagate a message in the actual forwarding direction to reduce the delay due to carry and forward. Through theoretical analysis and extensive simulation, it is shown that our link delay model provides the accurate link delay estimation in bidirectional city environments.
Identifying the dependency pattern of daily rainfall of Dhaka station in Bangladesh using Markov chain and logistic regression model  [PDF]
Mina Mahbub Hossain, Sayedul Anam
Agricultural Sciences (AS) , 2012, DOI: 10.4236/as.2012.33045
Abstract: Bangladesh is a subtropical monsoon climate characterized by wide seasonal variations in rainfall, moderately warm temperatures, and high humidity. Rainfall is the main source of irrigation water everywhere in the Bangladesh where the inhabitants derive their income primarily from farming. Stochastic rainfall models were concerned with the occurrence of wet day and depth of rainfall for different regions to model the daily occurrence of rainfall and achieved satisfactory results around the world. In connection to the Markov chain of different order, logistic regression is conducted to visualize the dependence of current rainfall upon the rainfall of previous two-time period. It had been shown that wet day of the previous two time period compared to the dry day of previous two time period influences positively the wet day of current time period, that is the dependency of dry-wet spell for the occurrence of rain in the rainy season from April to September in the study area. Daily data are collected from meteorological department of about 26 years on rainfall of Dhaka station during the period January 1985-August 2011 to conduct the study. The test result shows that the occurrence of rainfall follows a second order Markov chain and logistic regression also tells that dry followed by dry and wet followed by wet is more likely for the rainfall of Dhaka station and also the model could perform adequately for many applications of rainfall data satisfactorily.
Variable Charge of Ultisols due to Phosphate Application and Incubation Time
Muhammad Mahbub
Jurnal Tanah Tropika , 2010,
Abstract: The laboratoryexperiment was conducted to study the effect of phosphate (P) application and its incubation time on pHo (pH at thepoint of zero charge) and variable charge of ultisols . The determined parameters were pHo and variable surfacecharges.Soil samples were added by 0, 375 and 1,125 mg P kg-1 (or 0, 50 and 150% of the P sorption maximum,respectively). Then, they were incubated for 2, 4, 6 and 8 weeks. The variable surface-charges and pHo weredetermined by using the activity of potential determining ions (H+ and OH-) within two salt concentrations as counterions (0.1N and 0.001N CaCl2) through a potentiometric titration method. The results were indicated that the high Psorption and 766 mg P kg-1 in maximum sorption were due to high contents in clay fractions and aluminum as well aslow pH of experimental soil. Application of P and incubation time were able to decrease pHo and to increase negativesurface-charges. Additionals of 375 and 1.125 mg P kg-1 incubated for 8 weeks gave the value of pHo 2.86 and 2.69;as well as the magnitude of negative charges 14.48 and 16.76 cmol(-).kg-1, respectively (both for 0.001N CaCl2).For pH > pHo (the characteristic of variable charge soils), the higher the salt (CaCl2) concentration and pH solution,the higher the negative surface-charge.
Secondary Students’ Environmental Attitudes: The Case of Environmental Education in Bangladesh
Mahbub Sarkar
International Journal of Academic Research in Business and Social Sciences , 2011,
Abstract: This paper examined secondary students’ environmental attitudes in Bangladesh by employing a standardized environmental attitude scale. The scale consisted of 15 questions rated on a Likert-type scale ranging from 1 (strongly disagree) to 5 (strongly agree). 400 secondary students, with equal number of boys and girls from both the urban and rural schools participated in this study. The study found that overall students from both the urban and rural areas expressed favourable environmental attitudes with girls having a significantly higher level of favourable environmental attitudes than boys; in particular, rural girls had the highest level of environmental attitudes comparing among others. This paper discussed the scope for further research to identify the gap and relationship between environmental attitudes and environmental behaviours of Bangladeshi adolescents.
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