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Hysteretic Phenomenon of Shock Wave in a Supersonic Nozzle

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Journal of Thermal Science 2010年第6期19卷 526-532页

作者： Toshiaki Setoguchi Shigeru matsuo m.m. ashraful alam Junji Nagao Heuy Dong Kim Institute of Ocean Energy Saga University Department of Advanced Technology Fusion Saga University Graduate School of Science & Engineering Saga University School of mechanical Engineering Andong National University

In recent years, hysteretic phenomena in fluid flow systems drew attention for their great variety of industrial and engineering applications. When the high-pressure gas is exhausted to atmosphere from the nozzle exit, the expanded supersonic jet with the mach disk is formed at a specific condition. In two-dimensional expanded supersonic jet, the hysteresis phenomenon for the reflection type of shock wave is occurred under the quasi-steady flow and the transitional pressure ratio between the regular reflection and mach reflection is affected by this phe- nomenon. However, so far, there are very few researches for the hysteretic phenomenon of shock wave in a supersonic internal flow and the phenomenon has not been investigated satisfactorily. The present study was concemed with the experimental and numerical investigations of hysteretic phenomena of shock wave in a supersonic nozzle, and discussed the relationship between hysteresis phenomenon and rate of the change of pressure ratio with time.

关键词： compressible flow hysteresis internal flow shock wave supersonic nozzle

Turning Trash into Treasure: Developing an Intelligent Bin for Plastic Bottle Recycling

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Journal of Social Computing 2024年第1期5卷 1-14页

作者： Sirajam munira Niloy Paul md ashraful alam md.mahmudur Rahman m.Shamim Kaiser Institute of Information Technology Jahangirnagar UniversityDhaka 1342Bangladesh

Plastic pollution has emerged as a major global concern due to its enduring nature and limited recycling *** response to this critical challenge,this paper presents a novel approach utilizing a Detection-Based Reward System(DBRS)alongside an innovative business model to promote effective plastic waste management,reduce plastic waste accumulation in the nature,and uphold environmental *** the YOLOv5 algorithm for its exceptional accuracy,speed,and open-source availability,plastic bottle detection becomes a pivotal aspect of this *** seamlessly enroll in the system,triggering an automated detection process that computes reward points corresponding to their deposited plastic *** reward points are meticulously stored within a centralized *** its operational facets,this comprehensive system encompasses a robust business model,strategically poised to capture widespread engagement with waste disposal practices,thereby contributing to the realization of Sustainable Development Goals(SDGs)geared towards fostering a healthier ***,the DBRS attains cutting-edge performance in plastic bottle detection,boasting an impressive mean Average Precision(mAP)of 0.973,underscoring its efficacy in tackling plastic pollution.

关键词： smart environment reward system YOLOv5 deep learning business model

A Counter-Rotating Impulse Turbine for Wave Energy Conversion

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Open Journal of Fluid Dynamics 2018年第4期8卷 435-442页

作者： manabu Takao Kohei Yamada Shinya Okuhara m. m. ashraful alam Yoichi Kinoue Toshiaki Setoguchi Department of mechanical Engineering National Institute of Technology Matsue College Matsue Japan Advanced Course of Production and Construction Systems National Institute of Technology Matsue College Matsue Japan Support Center for Practical Education National Institute of Technology Matsue College Matsue Japan Department of mechanical Engineering Saga University Saga Japan Institute of Ocean Energy Saga University Saga Japan

Wave energy can be converted to the electrical energy by using a wave energy converter. The wave energy converter with oscillating water column (OWC) is one of the most promising devices because of its simple structure and easy maintenance. In this device, an oscillating water column due to the wave motion is used to drive an air column. An air turbine is used to convert the pneumatic energy of this bi-directional airflow into the mechanical energy. The counter-rotating impulse turbine for wave energy conversion has been proposed and tested so far, and the average efficiency has been shown to about 0.3. On the contrary, in another offshore experiment, it has been reported that the power generation efficiency of this turbine is larger than Wells turbine in case of small waves. However, there is a scarcity of the detailed characteristics data of counter-rotating impulse turbine. In a previous study, the authors investigated the effect of rotor blade solidity and setting angle of guide vane on the performance of this turbine, and they clarified that the efficiency of this turbine is higher than impulse turbine with single rotor in the range of high flow coefficients. The present study aimed to investigate the effect of rotor blade profile on the turbine performance by using the computation fluid dynamic (CFD) analysis. The inner and outer angles of turbine rotor blade are changed in the range of 50° to 70°. The commercial CFD software of SCRYU/Tetra of Cradle Co. Ltd. was used in the present work. The Reynolds averaged Navier-Stokes (RANS) equations were used as the governing equations and the low Reynold’s number SST k-ω model was used to predict the turbulent stresses. As a result, it was found that the inner angle of γ = 70° and the outer angle of γ = 60° of the turbine rotor blades can give the best turbine efficiency and it shows the efficiency close to the impulse turbine with single rotor, even in the range of low flow coefficients.

关键词： Air Turbine CFD Fluid machinery Oscillating Water Column (OWC) Wave Energy Conversion

Repercussion of salinity on hematological parameters and tissue morphology of gill and kidney at early life of tilapia

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Aquaculture and Fisheries 2024年第2期9卷 256-264页

作者： Azhar Ali md Golam Azom Bhakta Supratim Sarker Hasu Rani md Samsul alam m.sadiqul islam*department of fisheries biology and genetics bangladesh agricultural universitymymensingh2202bangladesh

This study was attempted to reveal the changes in three hematological parameters such as blood hemoglobin,number of white blood cells(WBCs)and number of red blood cells(RBCs)and one biochemical(e.g.,glucose)parameter along with the changes in histomorphological structures of gills and kidney of Nile tilapia fry reared in saline *** experimental set up were used for two different age groups-5 days-after-hatch(5DAH)and 15 days-after-hatch(15DAH)-to test a novel hypothesis:if a little difference in the age during the first exposure to saline water could produce any variation in the *** were placed into 6 plastic drums having six different salinity levels:0,5,10,15,20 and *** 60 days,at least 5 individuals were taken out from each drum to observe the above-hematological and histomorphological parameters.A two-way-ANOVA revealed that,except for hemoglobin,all the observed parameters have been affected the effect of age×salinity interaction(Pmean glucose value,RBC counts and WBC count at different salinities differed significantly from the base mean value of each *** regard to the histomorphological structure of the gills and kidney,various malformations were *** hypertrophy,epithelial uplifting and epithelial necrosis were present as gill degenerations,hyperplasia was prevalent across almost all salinity *** the other hand,glomerular necrosis,pyknotic nucleus,hyaline droplets degeneration,shrinking of the glomeruli,*** observed in kidney *** assisting to understand the effects of salinity stress,all these data on tilapia fry will help to determine the prospects and scope of culturing the species in high-salinity water.

关键词： Nile tilapia Salinity Blood parameters Histomorphology Age groups

Integrated Approaches of mechanical Barrier, Insecticide and Botanicals against mango mealybug (Drosicha mangiferae)

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Advances in Entomology 2024年第3期12卷 195-202页

作者： N. Akhter m. Z. alam m. A. Rahaman m. R. U. miah I. H. mian m. A. Latif Department of Entomology Faculty of Agriculture Sher-e-Bangla Agricultural University Dhaka Bangladesh Department of Entomology Faculty of Agriculture Bangabandhu Sheikh Mujibur Rahman Agricultural University Gazipur Bangladesh Department of Plant Pathology Faculty of Agriculture Sher-e-Bangla Agricultural University Dhaka Bangladesh Department of Plant Pathology Bangabandhu Sheikh Mujibur Rahman Agricultural University Gazipur Bangladesh

An experiment was conducted to test the efficacy of a mechanical barrier around the tree trunk with one spray of Cypermethrin @ 1 ml/l and turmeric powder extract @ 15 g/500ml of water applied in integrated approaches against mango mealybug on mango tree. There were 7 treatments including a control. The treatments were mechanical barrier, Cypermethrin spray @ 1 ml/l, Turmeric powder spray @ 15 g/500ml of water, Cypermethrin spray + Turmeric spray, Cypermethrin spray + mechanical barrier, Turmeric + mechanical barrier and untreated control. Three-year-old mango plants grafted from a 5-year-old mango tree (Variety Amropali) and planted in pots were used in the experiment. The treatment, Cypermethrin spray + mechanical barrier gave the highest reduction of mango mealybug population 87.06% to 93.90% followed by Turmeric spray + mechanical barrier and showed 81.13% to 86.04% and mechanical barrier alone showed 81.13% to 84.59% population reduction. Turmeric powder extract showed only (8.42% to 23.77%) population reduction of mango mealybug which was lowest compared to other treatments.

关键词： mango mealybug Integrated management

Source parameters and aftershock pattern of the October 7,2021,m5.9 Harnai earthquake,Pakistan

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Earthquake Science 2024年第4期37卷 304-323页

作者： mohammad Tahir Zeeshan Ahmad Sadia Sabahat muhammad Naveed mushtaq Talat Iqbal muhammad Ali Shah alam Aftab Centre for Earthquake Studies National Centre for PhysicsIslamabad 44000Pakistan

On October 7,2021,a magnitude 5.9 earthquake struck the Harnai(Baluchistan)region of Pakistan,causing several fatalities and injuries within the epicentral ***-order tectonic deformation in this region is caused by the convergence of the Indian Plate with respect to the Eurasian *** Katwaz Block hinders the motion of the Indian Plate,resulting in the formation of strike-slip *** this study,the P-wave first-motion polarity technique was used to determine the mainshock faulting *** scanning of the polarity solutions was applied to determine the most suitable focal mechanism solution among the available solutions generated by the FOCmEC(focal mechanism)*** nodal planes correspond to different faulting styles(i.e.,thrust and strike-slip faulting).A nodal plane oriented in the NW-SE direction corresponded to a strike-slip mechanism,which was considered to be the fault ***,this earthquake was associated with the Harnai-Karahi strike-slip fault zone owing to the fault strike and direction of *** apparent stress drop,fault length,and moment magnitude of the Harnai earthquake were 35.4 bar,6.1 km,and 5.9,respectively.A lower b-value for the Gutenberg-Richter law was observed prior to the ***α-than b-values(α>b)indicate that this earthquake was governed by large events as opposed to small-magnitude *** Harnai sequence had a decay exponent close to unity,lasted for 145 days,and produced few *** study will help the future hazard mitigation in the region.

关键词： focal mechanism solution selection of fault plane FPFIT stress inversion oblique slip mechanism

Oblique collisional effects of dust acoustic waves in unmagnetized dusty plasma

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Chinese Physics B 2020年第6期29卷 304-313页

作者： m S alam m R Talukder Department of mathematics Chittagong University of Engineering and TechnologyChittagong-4349Bangladesh Plasma Science and Technology Laboratory Department of Electrical and Electronic EngineeringUniversity of RajshahiRajshahi-6205Bangladesh

Effects of oblique collisions of the dust acoustic(DA)waves in dusty plasma are studied by considering unmagnetized fully ionized *** plasma consists of inertial warm negatively charged massive dusts,positively charged dusts,superthermal kappa distributed electrons,and isothermal *** extended Poincaré–Lighthill–Kuo(e PLK)method is employed for the drivation of two-sided Korteweg–de Vries(KdV)equations(KdVEs).The Kd V soliton solutions are derived by using the hyperbolic secant *** effects of superthermality index of electrons,temperature ratio of isothermal ion to electron,and the density ratio of isothermal ions to negatively charged massive dusts on nonlinear coefficients are *** effects of oblique collision on amplitude,phase shift,and potential profile of right traveling solitons of DA waves are also *** study reveals that the new nonlinear wave structures are produced in the colliding region due to head-on collision of the two counter propagating DA *** nonlinearity is found to decrease with the increasing density ratio of ion to negative dust in the critical *** phase shifts decrease(increase)with increasing the temperature ratio of ion to electron(κe).The hump(compressive,κeκec)solitons are produced depending on the angle(θ)of oblique collision between the two waves.

关键词： ion acoustic wave dusty plasma kappa distribution ePLK method hyperbolic secant method

Head-on collision between single-and multi-soliton heavy ion acoustic waves in multi-ion plasmas

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Plasma Science and Technology 2019年第9期21卷 58-72页

作者： m S alam m R TALUKDER Department of mathematics Chittagong University of Engineering and Technology Chittagong-4349 Bangladesh Plasma Science and Technology Lab Department of Electrical and Electronic Engineering University of Rajshahi Rajshahi-6205 Bangladesh

Head-on collisions among the single-and multi-soliton’s heavy ion acoustic waves(HIAWs) of multi-ion plasma are studied. The plasma consists of adiabatic positively charged inertial heavy ions, Boltzmann energy distributed light ions and kappa energy distributed electrons. The extended poincaré-Lighthill-Kuo(e PLK) method is applied for the derivation of two-sided Korteweg–de Vries(KdV) equations(KdVEs). The KdV single-soliton solutions(KdVSSs) are determined using the hyperbolic secant method and the KdV multi-soliton solutions(KdVmSs)are obtained using the Hirota method. The effects of superthermality of electrons, temperature ratios of electron to light ion and heavy ion to electron, and the density ratio of electron to heavy ion on phase shifts are investigated for the head-on collisions between two-soliton HIAWs. The effects of plasma parameters on angular frequency, phase speed, production of multi-soliton structures, and the head-on collisions among single-, double-, triple-, quadruple-, and quintuplesolitons are also studied.

关键词： HIAWs multi-soliton kappa-distribution ePLK method Hirotta's method multi-ion

Novel PCR primers to diagnose visceral Leishmaniasis using peripheral blood, spleen or bone marrow aspirates

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Asian Pacific Journal of Tropical medicine 2017年第8期10卷 819-824页

作者： mahbuba Khatun S m Sabbir alam Abed Hussain Khan mAnwar Hossain Jalaluddin ashraful Haq mdShariful alam Jilani mohammad Tariqur Rahman muhammad manjurul Karim Department of microbiology University of Dhaka Department of medicine Bangabandhu Sheikh Mujib Medical University Department of microbiology Ibrahim Medical College & BIRDEM Hospital Faculty of Dentistry University of Malaya

Objective: To establish a suitable method of diagnosis of visceral Leishmania sis(VL) using peripheral blood, spleen or bone marrow aspirates. methods: Peripheral blood, bone marrow and spleen aspirate samples were collected from clinically suspected VL patients(n=26). A new PCR primer pair(mK1F/R) was designed targeting kinetoplast mini circle DNA sequences of Leishmania donovani, and Leishmania infantum, and was used to diagnose VL along with some other established primers for VL in polymerase chain reactions. Test was validated by comparing with several other diagnostic methods. Results: The designed primer set showed 100% specificity and 98% sensitivity in detecting VL using blood samples, when compared with more invasive samples: bone marrow or spleen aspirates. Conclusions: The newly designed primer mK1F/R could be a better alternative for PCR based diagnosis of VL using less invasive sample, peripheral blood instead of bone marrow or spleen aspirates.

关键词： Visceral Leishmaniasis Kala-Azar Leishmania species PCR detection New primer