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Fluid Flow and Infrared Image Analyses on Endwall Fitted with Short Rectangular Plate Fin

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Journal of Thermal Science 2006年第2期15卷 145-151页

作者： Kenyu OYAKAWA Islam md. DIDARUL Minoru YAGA Dept. of Mechanical Systems Engineering University of the Ryukyus Okinawa Japan. Faculty of Engineering University of the Ryukyus Okinawa Japan.

An experimental investigation is carded out to study fluid flow and heat transfer characteristics on the endwall fitted with arrays （ 7 × 7 ） of short rectangular plate fins of different pattern （co-angular and zigzag） for different pitch ratio. Experiments were conducted in a rectangular duct of 50 mm height for an air flow of Reynolds number ranged from 18750 to 62500 based on the equivalent diameter and air velocity of the duct. Infrared image analysis technique was employed to make clear the characteristics of local heat transfer coefficients on fin base, endwall and overall surface. Flow pattern around the short rectangular plates were visualized by inducing fluorescent dye in a water channel and longitudinal vortices were observed. Increasing the distance between plates in flow direction causes heat transfer enhancement for co-angular pattern, while decreasing the distance causes heat transfer enhancement for zigzag pattern. Zigzag pattern with pitch ratio 2 is found to be more effective in heat transfer enhancement than any other cases investigated.

关键词： infrared image rectangular plate convection heat transfer flow visualization

Computational Study on a Squid-Like Underwater Robot with Two Undulating Side Fins

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Journal of Bionic Engineering 2011年第1期8卷 25-32页

作者： md. Mahbubar Rahman Yasuyuki Toda Hiroshi Miki Department of Naval Architecture and Ocean Engineering Graduate School of Engineering Osaka University 2-1 Yamadaoka Suita City Osaka 565-0871 Japan

The undulating fin propulsion system is an instance of the bio-inspired propulsion systems. In the current study, the swimming motion of a squid-like robot with two undulating side fins, mimicking those of a Stingray or a Cuttlefish, was investigated through flow computation around the body. We used the finite analytic method for space discretization and Euler implicit scheme for time discretization along with the PISO algorithm for velocity pressure coupling. A body-fitted moving grid was generated using the Poisson equation at each time step. Based on the computed results, we discussed the features of the flow field and hydrodynamic forces acting on the body and fin. A simple relationship among the fin＇s principal dimensions was established. Numerical computation was done for various aspect ratios, fin angles and frequencies in order to validate the proposed relationship among principal dimensions. Subsequently, the relationship was examined base on the distribution of pressure difference between upper and lower surfaces and the distribution of the thrust force. In efficiency calculations, the undulating fins showed promising results. Finally, for the fin, the open characteristics from computed data showed satisfactory conformity with the experimental results.

关键词： biomimetics squid robot undulating fin propulsion efficiency hydrodynamics CFD

Economic dependence of rural people on homestead forestry in Mymensingh, Bangladesh

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Journal of Forestry Research 2013年第3期24卷 591-597页

作者： Nur Muhammed md. Farhad Hossain Masum md. Mohitul Hossain Sheeladitya Chakma Gerhard Oesten Address - School of International Tropical Forestry Universiti Malaysia SabahJalan UMS 88400 Kota Kinabalu Sabah Malaysia Institute of Forestry and Environmental Sciences University of ChittagongBangladesh Institute of Forestry Economics University of FreiburgFreiburg Germany

Homestead forests contribute substantially to the rural econ- omy of Bangladesh. Rural people depend on trees and plants for their energy usage, housing, food and other forms of subsistence livelihood. In order to identify the potential role of forests on homestead dwellers, an empirical field investigation was conducted in the four Upazilas of My- mensingh district of Bangladesh. It was found that land holdings of the respondents within the four sites are the highest in Mymensingh. The study made an important observation that among all homestead vegeta- tion between 5-6 years old, tree species are generally preferred over plants. This is perhaps due to the efforts of the social forestry extension service to demonstrate that planting trees is an important long-term in- vestment. In all four Upazilas, there was a significant correlation between household annual income and homestead forestry, agriculture and fisher- ies practice, suggesting that higher income families tend to have larger holdings of homesteads, farms and pond areas. Three Upazilas displayed a strong positive relationship （nearly 45%） between homestead forest areas and annual family income; however, the Fulbaria Upazila showed a very poor relationship （0.2%） in this regard. The results of this study suggest that homestead forests play a positive role in the rural economy, in addition to helping mitigate the increasing problem of deforestation in Bangladesh.

关键词： economic dependence homestead Bangladesh forestry

Energy Fluctuation of Ideal Fermi Gas Trapped under Generic Power Law Potential U=Σ_(i=1)~d c_i|x_i/a_i|^(n_i) in d Dimensions

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Communications in Theoretical Physics 2016年第4期65卷 465-468页

作者： Mir mehedi Faruk md.Muktadir Rahman Dwaipayan Debnath md.Sakhawat Hossain Himel Theoretical Physics Blackett LaboratoryImperial College Department of Theoretical Physics University of Dhaka Department of Biomedical Physics and Technology University of Dhaka

Energy fluctuation of ideal Fermi gas trapped under generic power law potential U=Σ_(i=1)~d c_i|x_i/a_i|^(n_i) has been calculated in arbitrary *** fluctuation is scrutinized further in the degenerate limit μ>>K_B T with the help of Sommerfeld *** dependence of energy fluctuation on dimensionality and power law potential is studied in *** importantly our general result can not only exactly reproduce the recently published result regarding free and harmonically trapped ideal Fermi gas in d =3 but also can describe the outcome for any power law potential in arbitrary dimension.

关键词： Fermi gas power law potential energy fluctuation

Biomass and net primary productivity of mangrove communities along the Oligohaline zone of Sundarbans, Bangladesh

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Forest Ecosystems 2017年第4期4卷 264-272页

作者： md. Kamruzzaman Shamim Ahmed Akira Osawa Laboratory of Ecosystem Production and Dynamics Graduate School of Global Environmental Studies Kyoto University Kyoto 606-8501 Japan Forestry and Wood Technology Discipline Khulna University Khulna 9208 Bangladesh

Background： The article presents the first estimates of biomass and productivity for mangrove forests along the Oligohaline zone of the Sundarbans Reserve Forest （SRF）, Bangladesh. This study was conducted overone year from March 2016 to April 20] 7. Stand structure, above and below-ground biomass changes, and litterfall production were measured within a 2100 m2 sample plot. Methods： All trees in the study plots were numbered and height （H） and diameter at breast height （DBH） were measured. Tree height （H） and DBH for each tree were measured in March 2016 and 2017. We apply the above and belowground biomass equation for estimating the biomass of the mangrove tree species （Chave et al. Oecologia 145：87-99, 2005; Komiyama et al. J Trop Ecol 21：471-477, 2005）. Litterfall was collected using 1-mm mesh litter traps with collection area of 0.42 m2. Net Primary Production （NPP） was estimated by the summation method of Ogawa Primary productivity of Japanese forests： productivity of terrestrial communities, JIBP synthesis （1977） and Matsuura and Kajimoto Carbon dynamics of terrestrial ecosystem： Systems approach to global environment （2013）. Results： Heritiero fomes has maintained its dominance of the stand and also suffered the highest tree mortality （2.4%） in the suppressed crown class. The total above-ground biomass （AGB） and below-ground biomass （BGB） of the studied stand was ]54.8 and 84.2 ***-1, respectively. Among the total biomass of the trees, 64.8% was allocated to AGB and 35.2% to BGB. In case of species-wise contribution of biomass allocation, Avicennia officinalis showed the highest score and Aglaia cucullota the lowest. Mean annual total litterfall was 10.1 Mg-ha ***-1, with the maximum litterfall in winter or dry season and late summer or rainy season. The mean AGB increment and above-ground net primary productivity （AGNPP） were 7.1 and 17.2 ***-1, respectively. Total net primary productivity （NPP） was estimated to be 21.0 *** Lyr-1 over the observ

关键词： Primary production Litterfall Monthly pattern Biomass carbon Species wise contribution Sundarbans

Data-driven next-generation smart grid towards sustainable energy evolution: techniques and technology review

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Protection and Control of Modern Power Systems 2023年第3期8卷 97-138页

作者： Faiaz Ahsan Nazia hasan Dana Subrata K.Sarker Li Li S.M.Muyeen md.Firoj Ali Zinat Tasneem md.mehedi hasan Sarafat Hussain Abhi md.Robiul Islam md.Hafiz Ahamed md.Manirul Islam Sajal K.Das md.Faisal R.Badal Prangon Das Department of Mechatronics Engineering Rajshahi University of Engineering and TechnologyRajshahiBangladesh School of Electrical and Data Engineering Faculty of Engineering and ITUniversity of Technology SydneyUltimoAustralia Electrical Engineering Department Qatar UniversityDohaQatar

Meteorological changes urge engineering communities to look for sustainable and clean energy technologies to keep the environment safe by reducing CO_(2) *** structure of these technologies relies on the deep inte-gration of advanced data-driven techniques which can ensure efficient energy generation,transmission,and *** conducting thorough research for more than a decade,the concept of the smart grid(SG)has emerged,and its practice around the world paves the ways for efficient use of reliable energy ***,many developing features evoke keen interest and their improvements can be regarded as the next-generation smart grid(NGSG).Also,to deal with the non-linearity and uncertainty,the emergence of data-driven NGSG technology can become a great initiative to reduce the diverse impact of *** paper exhibits the conceptual framework of NGSG by enabling some intelligent technical features to ensure its reliable operation,including intelligent control,agent-based energy conversion,edge computing for energy management,internet of things(IoT)enabled inverter,agent-oriented demand side management,***,a study on the development of data-driven NGSG is discussed to facilitate the use of emerging data-driven techniques(DDTs)for the sustainable operation of the *** prospects of DDTs in the NGSG and their adaptation challenges in real-time are also explored in this paper from various points of view including engineering,technology,et ***,the trends of DDTs towards securing sustainable and clean energy evolution from the NGSG technology in order to keep the environment safe is also studied,while some major future issues are *** paper can offer extended support for engineers and researchers in the context of data-driven technology and the SG.

关键词： Data-driven technology Smart grid Sustainable energy evolution Next-generation smart grid Intelligent

Floristic composition and management of cropland agroforest in southwestern Bangladesh

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Journal of Forestry Research 2014年第3期25卷 597-604页

作者： md. hasanuzzaman Mahmood Hossain Mustafa Saroar Forestry and Wood Technology Discipline Khulna University Urban and Rural Planning Discipline Khulna University

Cropland agroforest is an important production system in the southwest region of Bangladesh. This study focused on the floristic composition and management of existing cropland agroforests. A total of 313 cropland agroforests were surveyed and 83%respondents practiced pure agroforestry while the remaining 17% practiced agroforestry with fisheries. A total of 18 forest trees and 2 shrubs were recorded from 11 families and 59 species of agricultural crops were from 28 families. A higher proportion （79%） of cropland agroforests were occupied small land areas （0.12-0.80 ha）. About 63% of respondents planted trees for fruit production and 47%for timber production, and 35%of respondents engaged in commercial production （35%）. Swietenia macrophylla was the most prevalent species （relative prevalence 20.83） followed by Man-gifera indica （relative prevalence 15.57） and Cocos nucifera （relative prevalence 7.08）. Shorter spacing was used for timber and fuel wood species and wider spacing for fruit trees. A wide range of rotation periods, from 5 to 25 years, was observed for both cases. The use of chemical fertilizer was highest followed by cow dung and compost in cropland agroforests. Overall management practices of cropland agroforest in southwest Bangladesh were determined by the end product and local demand.

关键词： agroforestry Bangladesh cropland fruit production timber production

Forest-based betel leaf and betel nut farming of the Khasia indigenous People in Bangladesh: approach to biodiversity conservation in Lawachara National Park(LNP)

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Journal of Forestry Research 2014年第2期25卷 419-427页

作者： md. Jahirul Islam Tapan Kumar Nath Bangladesh Planning Commission Institute of Forestry and Environmental Sciences University of Chittagong

An exploratory survey was conducted among the Khasia living in Lawachara National Parkt （LNP） to investigate their depend- ency on the protected area （PA） for livelihoods, betel leaf hill farming, traditional forest conservation and perceptions of the PA, Field data were collected by interviewing 48 household heads from two villages （punjis） located inside the LNP and visiting their farms.： The economy of the Khasia was forest-based. They were largely dependent on betel leaf hill farming in LNP and nearly 71% of their mean annual income was de- rived from this irrespective of farmer category. On average, about 14% of the incomes of the poorer farmers came from forest produce followed by 10% and 6% for medium and rich farmers respectively. Hills and forests were the foundations of their lives and livelihoods, and LNP was the life-blood of Khasia survival. As a sustainable production system, this farming practice plays a vital role in conserving biodiversity in LNP and might be replicated elsewhere.

关键词： Bangladesh indigenous people Khasia livelihoods betel leaf fanning protected area management

Describing Fuzzy Membership Function and Detecting the Outlier by Using Five Number Summary of Data

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American Journal of Computational Mathematics 2020年第3期10卷 410-424页

作者： md. Farooq hasan md. Abdus Sobhan Department of Mathematics and Statistics Bangladesh University of Business and Technology Dhaka Bangladesh

One of the most important activities in data science is defining a membership function in fuzzy system. Although there are few ways to describe membership function like artificial neural networks, genetic algorithms etc.;they are very complex and time consuming. On the other hand, the presence of outlier in a data set produces deceptive results in the modeling. So it is important to detect and eliminate them to prevent their negative effect on the modeling. This paper describes a new and simple way of constructing fuzzy membership function by using five-number summary of a data set. Five states membership function can be created in this new method. At the same time, if there is any outlier in the data set, it can be detected with the help of this method. Usually box plot is used to identify the outliers of a data set. So along with the new approach, the box plot has also been drawn so that it is understood that the results obtained in the new method are accurate. Several real life examples and their analysis have been discussed with graph to demonstrate the potential of the proposed method. The results obtained show that the proposed method has given good results. In the case of outlier, the proposed method and the box plot method have shown similar results. Primary advantage of this new procedure is that it is not as expensive as neural networks, and genetic algorithms.

关键词： Fuzzy Set Membership Function Five Number Summary Outliers