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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

Multiuser Detection for MIMO-OFDM system in Underwater Communication Using a Hybrid Bionic Binary Spotted Hyena Optimizer

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Journal of Bionic Engineering 2021年第2期18卷 462-472页

作者： md.Rizwan khan Bikramaditya Das Department of Electronics&Telecommunication Engineering VSS University of TechnologyBurla-768018OdishaIndia

Multi Access Interference (MAI) is the main source limiting the capacity and quality of the Multiple-Input Multiple-Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) system which fulfills the demand of high-speed transmission rate and high quality of service for future underwater acoustic (UWA) communication. Multi User Detection (MUD) is needed to overcome the performance degradation caused by MAI. In this research, both local and global optimal solutions are obtained in Bionic Binary Spotted Hyena Optimizer (BBSHO) algorithm using the Position Coordinate Vectors (PCVs) of the social behavior of spotted hyenas to achieve MUD. Further, Extremal Optimization (EO) is introduced in BBSHO algorithm to improve the local search ability within the search space. Hence, a hybrid BBSHO algorithm is proposed for achieving MUD at the receiver of the MIMO-OFDM system whose transceiver model in underwater is implemented using BELLHOP simulation system. By MATLAB simulation, it is shown that the Bit Error Rate (BER) performance of the proposed hybrid algorithm outperforms with best optimal solution within the search space towards MUD for Interference to Noise Ratio (INR) at 10 dB, 20 dB, and 40 dB over conventional detectors and metaheuristic approaches such as Binary Spotted Hyena Optimizer (BSHO), Binary Particle Swarm Optimization (BPSO) in the UWA network.

关键词： Underwater Acoustic(UWA) Orthogonal Frequency Division Multiplexing(OFDM) Multiuser Detection(MUD) Multi-Access Interference(MAI) Bionic Binary Spotted Hyena Optimizer(BBSHO) Extremal Optimization(EO)

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

HBsAg, HBcAg, and combined HBsAg/HBcAg-based therapeutic vaccines in treating chronic hepatitis B virus infection

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Hepatobiliary & Pancreatic Diseases International 2013年第4期12卷 363-369页

作者： Sheikh Mohammad Fazle Akbar Mamun Al-Mahtab Mohammad Helal Uddin md. Sakirul Islam khan Department of Medical Sciences Toshiba General HospitalTokyo Japan Department of Hepatology Bangabandhu Sheikh Mujib Medical UniversityDhaka Bangladesh Clinical Research Organization Dhaka Bangladesh Laboratory of Animal Production Faculty of Agriculture Ehime UniversityMatsuyama Japan

BACKGROUND: As the host immunity is diminished in patients with chronic hepatitis B (CHB), different approaches have been used to up-regulate their immune responses to produce therapeutic effects. But, cytokines, growth factors and polyclonal immune modulators could not exhibit sufficient therapeutic effects in these patients. Immune therapy with HBV-related antigens (vaccine therapy) has been used in CHB patients. But there is a paucity of information about the design of HBV antigen-based immune therapy in these patients. DATA SOURCE: Preclinical and clinical studies on immune therapy with HBsAg-based vaccine, HBcAg and combination of HBsAg/HBcAg-based vaccines have been discussed. RESULTS: HBsAg-based prophylactic vaccine was used as an immune therapeutic agent in CHB patients; however, monotherapy with HBsAg-based immune therapy could not lead to sustained control of HBV replication and/or liver damages. HBsAg-based vaccine was used as a combination therapy with cytokines, growth factors, and antiviral drugs. HBsAg-based vaccine was also used for cell-based therapy. However, satisfactory therapeutic effects of HBsAg-based vaccine could not be documented in CHB patients. In the mean time, evidences have supported that HBcAg-specific immunity is endowed with antiviral and liver protecting capacities in CHB patients. Recent data concentrate on the clinical use of combined HBsAg- and HBcAg-based vaccines in CHB ***: Antigen-based immune therapy with HBV- related antigens may be an alternative method for the treatment of CHB patients but proper designs of antigens, types of adjuvants, dose of vaccinations, and routes of administration need further analyses for the development of an effective regimen of immune therapy against HBV.

关键词： chronic hepatitis B HBsAg vaccine HBsAg/HBcAg vaccine immune therapy therapeutic vaccines

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

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

The Effect of Non-Equilibrium Condensation on Supersonic Air Flows over Rectangular Cavities

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Journal of Thermal Science 2007年第1期16卷 33-39页

作者： Miah md. Ashraful ALAM md. Mahbubul ALAM Shigeru MATSUO Kenbu TERAMOTO Toshiaki SETOGUCHI Heuy Dong KIM Shen YU Department of Mechanical Engineering Khulna University of Engineering ＆ Technology Khulna-9203 Bangladesh Department of Mechanical Engineering Saga University 1 Honjo-machi Saga-shi Saga 840-8502 Japan School of Mechanical Engineering College of Natural Science Andong National University 388 Song Cheon Dong Andong Kyung Pook Republic of Korea Institute of Engineering Thermophysics Chinese Academy of Sciences EO. Box 2706 Beijing 100080 China

Numerical simulations have been carded out for a supersonic two-dimensional flow over open, rectangular cavities （length-to-depth ratios are L/D = 1.0 and 3.0） in order to investigate the effect of non-equilibrium condensation of moist air on supersonic internal flows around the cavity for the flow Mach number 1.83 at the cavity entrance. In the present computational investigation, a condensing flow was produced by an expansion of moist air in a Laval nozzle. The computational results showed that the upstream traveling compression waves become weaker than those without the condensation. Consequently, the weaker compression waves cannot excite the shear layer strongly and amplitudes of oscillation in the cavity became smaller than those without the condensation. The occurrence of the non-equilibrium condensation in case of L/D = 1.0 affected strongly the amplitude and frequency of oscillation in the cavity compared with L/D = 3.0.

关键词： compressible flow supersonic cavity oscillation non-equilibrium condensation numerical simulation