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Search Results: 1 - 10 of 6453 matches for " Md. Arif Chowdhury "
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Status of Rohingya Refugees in Bangladesh: A Comparative Study with Emphasis on Aspects of Women and Girls in Camps of Kutupalong, Cox’s Bazar, Bangladesh  [PDF]
Shahnam Karin, Md. Arif Chowdhury, Ishrat Shamim
Open Access Library Journal (OALib Journal) , 2020, DOI: 10.4236/oalib.1105831
Abstract:
A continuous flow of Rohingya refugees in Bangladesh because of violence in Rakhine State in Myanmar causes consequence to the world’s largest refugee camp where most of the refugees are women and children. This study was conducted in 2018 in Bangladesh to understand the comparative status of registered and newly arrived Rohingya people in Kutupalong camps of Cox’s Bazar focusing the present conditions of women and girls. This research explores the comparative information of registered and newly arrived Rohingya refugee from different perspectives: basic demographic and socio-economic characteristics, shelter, food, water and sanitation, safety and security concerns, knowledge and education. In addition, this research also addressed the urgency of coping strategies of refugees in camps and all of the identified issues in this paper were also analysed from gender perspective too. This study will help different level stakeholders to take proper steps regarding the management of Rohingya refugees in Kutupalong of Cox Bazar, Bangladesh.
Capacitance-Voltage Characteristics of Nanowire Trigate MOSFET Considering Wave Function Penetration
Md. Alamgir Hossain,Arif Mahmud,Mahfuzul Haque Chowdhury,Md. Mijanur Rahman
International Journal of Electrical and Computer Engineering , 2012, DOI: 10.11591/ijece.v2i6.1785
Abstract: Short channel effects on the gate capacitance of nanowire trigate MOS field-effect transistors are studied considering wave function penetration. Capacitance-Voltage (C V) measurements are commonly used in studying gate-oxide quality in detail. C V test results offer a wealth of device and process information, including bulk and interface charges. Capacitance indicates switching speed of the MOSFET. It is our goal to minimize capacitance as possible as we can in MOSFET. Due to our necessary to compact the Integrated Circuit as possible as we can for getting small electronics devices. Capacitance determines the speed of the IC. Every engineer in this section should know capacitance of his implementing device MOSFET to get exact result from this device. Whenever we deal with 10X10 nm scale or less device of MOSFET. We must concern the effect of wave function penetration into device in this stage classical mechanics fails to describe exact result of the system because electron can move in only one direction (x), in 3 Dimension, it cannot move in other two direction (y, z). i.e. confined in two direction which is not predictable by classical mechanics here quantum mechanics (QM) gives better solution of this problem. Therefore we consider QM in our study. Here we presented how wave function play vital role considering small area of trigate MOSFET. It is the analytical approach of QM and highly recommendation to use QM rather than CM to get accuracy. This result will be helpful for determining capacitance of trigate MOSFET.
Performance Evaluation of a miniPET Camera for Brain Scanning  [PDF]
Arif Mahmud, Md. Moshiur Rahman
International Journal of Medical Physics,Clinical Engineering and Radiation Oncology (IJMPCERO) , 2015, DOI: 10.4236/ijmpcero.2015.41010
Abstract:
A nuclear miniPET camera was constructed with 2 bucket rings, each having 8 BGO detector modules for brain scanning. After calibration of the camera, an experimental investigation of sensitivity was carried out to evaluate the performance of this PET scanner. The characteristics of NECR were examined for comparisons of count rate considering the statistical noise due to scattered and random events. NECR performance was observed using 10 cm diameter phantom filled with 1 L water and 240 MBq of 18F. All data were acquired in 2D acquisition mode but without septa. Randoms were estimated by introducing delay into the coincidence circuit which was an extra 100 ns time delay. Multiples were recorded simultaneously with the prompt and delayed events. The true plus scattered coincidence events were calculated as the difference between prompt and random plus multiple events. After recording all the data, the noise equivalent count rate (NECR) was calculated and graphically presented. It is observed that NEC value is significantly lower than other similar scanners. Comparing the individual components of the count rate, a much higher randoms rate is observed for the camera because of the absence of any side shielding, so that out of field activity contributes significantly to the randoms rate and hence reduces the NECR value.
Mobility Issue on Octagonal Structured ZigBee Network Using Riverbed  [PDF]
Nazrul Islam, Md. Jaminul Haque Biddut, Md. Faizul Huq Arif, Mohammad Motiur Rahman, Md. Syfur Rahman
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2016, DOI: 10.4236/ijcns.2016.93005
Abstract: Wireless Sensor Network (WSN) is a special type of communication medium through distributed sensor nodes. Popular wireless sensor nodes like ZigBee have splendid interoperability after IEEE 802.15.4 standardization in the domain of wireless personal area network (WPAN). ZigBee has another great feature mobility that makes the ZigBee network more versatile. The mobility feature of ZigBee mobile nodes has a greater impact on network performance than fixed nodes. This impact sometimes turns into more severe because of network structure and mobility model. This study mainly focuses on the performance analysis of the ZigBee mobile node under Random and Octagonal mobility management model with the Tree routing method. The Riverbed academic modeler is used to design, implement and simulate the ZigBee network under certain conditions. This study also presents a competitive performance analysis based on ZigBee mobile nodes transmitter and receiver characteristics under the observation of the mobility model. This indicates that Octagonal mobility model exhibits better performance than the Random mobility model. This study will constitute a new way for further designing and planning a reliable and efficient ZigBee network.
The Cognitive Foundations of Partitioned Country-of-Origin: A Causal Path Analysis
Md. Humayun Kabir Chowdhury
International Journal of Marketing Studies , 2010, DOI: 10.5539/ijms.v2n2p258
Abstract: This paper proposes a framework for the analysis of partitioned country-of-origin associations on consumer product quality evaluations. This research clarifies the roles of country-of-design, country-of-assembly, country-of-parts and brand image in evaluating consumer perceptions of product quality. Data were analyzed via structural equation models using Amos 5.0. Results from structural equations analysis reveal a broader conceptualization of consumer perceived quality in Bangladesh as reflected in the model. In particular it was found that for high involvement products like television, perceived country-of-origin association instead of brand image significantly influence in shaping perceptions of quality in the country.
Short-Term Financial Time Series Forecasting Integrating Principal Component Analysis and Independent Component Analysis with Support Vector Regression  [PDF]
Utpala Nanda Chowdhury, Sanjoy Kumar Chakravarty, Md. Tanvir Hossain
Journal of Computer and Communications (JCC) , 2018, DOI: 10.4236/jcc.2018.63004
Abstract: Financial time series forecasting could be beneficial for individual as well as institutional investors. But, the high noise and complexity residing in the financial data make this job extremely challenging. Over the years, many researchers have used support vector regression (SVR) quite successfully to conquer this challenge. In this paper, an SVR based forecasting model is proposed which first uses the principal component analysis (PCA) to extract the low-dimensional and efficient feature information, and then uses the independent component analysis (ICA) to preprocess the extracted features to nullify the influence of noise in the features. Experiments were carried out based on 16 years’ historical data of three prominent stocks from three different sectors listed in Dhaka Stock Exchange (DSE), Bangladesh. The predictions were made for 1 to 4 days in advance targeting the short term prediction. For comparison, the integration of PCA with SVR (PCA-SVR), ICA with SVR (ICA-SVR) and single SVR approaches were applied to evaluate the prediction accuracy of the proposed approach. Experimental results show that the proposed model (PCA-ICA-SVR) outperforms the PCA-SVR, ICA-SVR and single SVR methods.
Grid-Connected Emergency Back-Up Power Supply  [PDF]
Dhiman Chowdhury, Mohammad Sharif Miah, Md. F. Hossain
Circuits and Systems (CS) , 2019, DOI: 10.4236/cs.2019.101001
Abstract: This paper documents design and modeling of a grid-connected emergency back-up power supply for medium power applications. Back-up power supplies are very important in regard to support electrical loads in the events of grid power outage. However, grid-integration of a back-up power supply substantiates continual power transfer to the loads, especially to the critical loads, which should not suffer from power interruptions. Therefore, design and circuit modeling of switching converters based reliable grid-tied emergency back-up power supply are presented in this paper. There are a rectifier-link boost derived battery charging circuit and a 4-switch push-pull power inverter circuit which are controlled by high frequency pulse width modulation (PWM) signals. This paper presents a state averaging model and Laplace domain transfer function of the charging circuit and a switching converter model of the power inverter circuit. A changeover relay based transfer switch controls the power flow towards the utility loads. During off-grid situations, loads are fed power by the proposed inverter circuit and during on-grid situations, battery is charged by an ac-link rectifier-fed boost converter. However, there is a relay switching circuit to control the charging phenomenon of the battery. The proposed design is simulated in PLECS and the simulation results corroborate the reliability of the presented framework.
Effects of Cultural Conditions on High Temperature Tolerance of Lentinula edodes Mycelia
Md. Arif Mahmud,Masatake Ohmasa
Pakistan Journal of Biological Sciences , 2008,
Abstract: The effects of several cultural conditions on high temperature tolerance of vegetative mycelia of five Lentinula edodes strains were investigated. Mycelium of longer culture age (70 days) was significantly shown high temperature tolerance compared to mycelium of shorter culture ages (14 and 30 days) for four strains, whereas SA142 that showed reverse. When the culture plates were pretreated at 30 and 33°C for 48 h incubation before heat treatment (40°C, 8 h), mycelia of L. edodes strains were shown high temperature tolerance. Effects of nutritional factors in BM (basic medium) for the high temperature tolerance of L. edodes strains were also investigated. While yeast extract (as nitrogen source) and starch (as carbon source) were added to BM media, as a result cultured vegetative mycelia of L. edodes strains were significantly shown high temperature tolerance against heat treatment (40°C, 6 and 8 h). Further more, addition of bases (adenine + cytosine), vitamin (biotin) and organic acid (tartaric acid) to BM media, consequently vegetative mycelia of some L. edodes strains were also effective to increase high temperature tolerance.
Modeling of Orientation-Dependent Photoelastic Constants in Cubic Crystal System  [PDF]
Lubna Jahan Rashid Pinky, Shakila Islam, Md. Nur Kutubul Alam, Mohammad Arif Hossain, Md. Rafiqul Islam
Materials Sciences and Applications (MSA) , 2014, DOI: 10.4236/msa.2014.54027
Abstract:

Euler’s rotation theorem and tensor rotation technique are applied to develop a generalized mathematical model for determining photoelastic constants in arbitrary orientation of cubic crystal system. Two times rotations are utilized in the model relating to crystallographic coordinates with Cartesian coordinates. The symmetry of photoelastic constants is found to have strong dependence with rotation angle. Using the model, one can determine photoelastic constants in any orientation by selecting appropriate rotation angle. The outcome of this study helps to characterize spatial variation of residual strain in crystalline as well as polycrystalline materials having cubic structure using the experimental technique known as scanning infrared polariscope.

Sustainable Use of Steel Industry Slag (SIS) for Concrete Production: A State Art of Review  [PDF]
Md. Muzammel Hoque, Md. Arif Hosse
Open Journal of Applied Sciences (OJAppS) , 2019, DOI: 10.4236/ojapps.2019.912067
Abstract: This paper presents a review on the sustainable use of steel industry slag (SIS) in the construction industry for sustainable development. This issue also may contribute significantly to attain the sustainable development goal (SDG). If feasible sector is not determined earlier for the use of SIS for the country like Bangladesh then the unproductive uses will be increased and as well without large-scale utilization, direct dumping of SIS will create environmental hazards. On the other hand, the sustainable use of SIS in concrete production can contribute to the economic growth of the country; in addition, it can also contribute to keeping our natural environment safe from hazardous pollution. Another observation of this study is SIS used in cement and concrete production as aggregate or as additional cementing materials has a long-term strength and durability. Besides, replacement of cement with SIS deferred the hydration reaction at early ages, without any significant troubles. Furthermore, it can also be mentioned that high replacement of SIS with cement may raise a problem of volume instability which can be solved by using ground-granulated blast-furnace slag (GGBS) as combined admixture and the slump problem of concrete mixtures can be adjusted with addition of copper slag or class F fly ash. Feasibility analysis of SIS usage and an awareness program for all the stakeholders may be implemented for the sustainable uses of SIS. Both of these will play a vital role to safeguard environment in addition to economic growth of the country.
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