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CFD study of turbulent jet impingement on curved surface

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Chinese Journal of Chemical Engineering 2016年第5期24卷 588-596页

作者： Javad Taghinia md Mizanur rahman Timo Siikonen Aalto University School of EngineeringDepartment of Applied MechanicsFI-00076Finland Hong Kong University of Science and Technology Department of Civil and Environmental EngineeringClear Water BayHong KongChina

The heat transfer and flow characteristics of air jet impingement on a curved surface are investigated with computational fluid dynamics(CFD)*** first applied model is a one-equation SGS model for large eddy simulation(LES)and the second one is the SST-SAS hybrid *** models are utilized to study the flow physics in impinging process on a curved surface for different jet-to-surface(h/B)distances at two Reynolds numbers namely,2960 and 4740 based on the jet exit velocity(U_e)and the hydraulic diameter(2B).The predictions are compared with the experimental data in the literature and also the results from RANS k-ε*** show that both models can produce relatively good ***,one-equation model(OEM)produced more accurate results especially at impingement region at lower jet-to-surface *** terms of heat transfer,the OEM also predicted better at different jet-to-surface *** is also observed that both models show similar performance at higher h/B ratios.

关键词： Jet impingement Curved surface RAST one-equation model Large eddy simulation Heat transfer

Active Cell Balancing Control Strategy for Parallelly Connected LiFePO_(4) Batteries

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CSEE Journal of Power and Energy Systems 2021年第1期7卷 86-92页

作者： md Ohirul Qays Yonis Buswig md Liton Hossain md Momtazur rahman Ahmed Abu-Siada Department of Electrical and Electrical Engineering Faculty of EngineeringUniversity Malaysia SarawakKota SamarahanSarawakMalaysia Department of Electrical and Computer Engineering Curtin UniversityKent StreetBentleyPerth 6102WAAustralia Electron Science Research Institute Edith Cowan University270 Joondalup DriveJoondalupWA6027Australia

While several recent studies have focused on elimi-nating the imbalance of energy stored in series-connected battery cells,very little attention has been given to balancing the energy stored in parallel-connected battery *** such,this paper aims at presenting a new balancing approach for parallel LiFePO_(4) battery *** this regard,a Backpropagation Neural Network(BPNN)based technique is employed to develop a Battery Management System(BMS)that can assess the charging status of all cells and control its operations through a DC/DC Buck-Boost *** results demonstrate the effectiveness of the proposed approach in balancing the energy stored in parallel-connected battery cells in which the state of charge(SoC)estimation error is found to be only 1.15%.

关键词： Active cell balancing battery management system DC/DC buck-boost converter state of charge estimation

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

Robustness Study and Superior Method Development and Validation for Analytical Assay Method of Atropine Sulfate in Pharmaceutical Ophthalmic Solution

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American Journal of Analytical Chemistry 2024年第5期15卷 151-164页

作者： md. Nazmus Sakib Chowdhury Sreekanta Nath Dalal md. Ariful Islam md. Anwar Hossain Pranab Kumar Das Shakawat Hossain Parajit Das Department of Pharmacy Bangabandhu Sheikh Mujibur Rahman Science and Technology University Gopalganj Bangladesh Department of Applied Chemistry and Chemical Engineering University of Dhaka Dhaka Bangladesh Department of Applied Chemistry and Chemical Engineering University of Chittagong Chattogram Bangladesh Department of Applied Chemistry and Chemical Engineering Islamic University Kushtia Bangladesh Department of Applied Chemistry and Chemical Engineering University of Rajshahi Rajshahi Bangladesh Department of Pharmacy International Islamic University Chittagong Chittagong Bangladesh Department of Applied Chemistry and Chemical Engineering Bangabandhu Sheikh Mujibur Rahman Science and Technology University Gopalganj Bangladesh

Background: The robustness is a measurement of an analytical chemical method and its ability to contain unaffected by little with deliberate variation of analytical chemical method parameters. The analytical chemical method variation parameters are based on pH variability of buffer solution of mobile phase, organic ratio composition changes, stationary phase (column) manufacture, brand name and lot number variation;flow rate variation and temperature variation of chromatographic system. The analytical chemical method for assay of Atropine Sulfate conducted for robustness evaluation. The typical variation considered for mobile phase organic ratio change, change of pH, change of temperature, change of flow rate, change of column etc. Purpose: The aim of this study is to develop a cost effective, short run time and robust analytical chemical method for the assay quantification of Atropine in Pharmaceutical Ophthalmic Solution. This will help to make analytical decisions quickly for research and development scientists as well as will help with quality control product release for patient consumption. This analytical method will help to meet the market demand through quick quality control test of Atropine Ophthalmic Solution and it is very easy for maintaining (GDP) good documentation practices within the shortest period of time. Method: HPLC method has been selected for developing superior method to Compendial method. Both the compendial HPLC method and developed HPLC method was run into the same HPLC system to prove the superiority of developed method. Sensitivity, precision, reproducibility, accuracy parameters were considered for superiority of method. Mobile phase ratio change, pH of buffer solution, change of stationary phase temperature, change of flow rate and change of column were taken into consideration for robustness study of the developed method. Results: The limit of quantitation (LOQ) of developed method was much low than the compendial method. The % RSD fo

关键词： Robustness Method Validation HPLC Compendial Method Method Development GDP LOQ

Efficient Algorithm for Prolonging Network Lifetime of Wireless Sensor Networks

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Tsinghua Science and Technology 2011年第6期16卷 561-568页

作者： md Nafees rahman M A Matin Department of Electrical Engineering and Computer Science North South University

One of the fundamental design challenges in designing a Wireless Sensor Network （WSN） is to maximize the network lifetime, as each sensor node of the network is equipped with a limited power battery. To overcome this challenge, different methods were developed in the last few years using such techniques as network protocols, data fusion algorithms using low power, energy efficient routing, and locating optimal sink position. This paper focuses on finding the optimal sink position. Relay nodes are introduced in conjunction with the sensor nodes to mitigate network geometric deficiencies since in most other approaches the sensor nodes close to the sink become heavily involved in data forwarding and, thus, their batteries are quickly depleted. A Particle Swarm Optimization （PSO） based algorithm is used to locate the optimal sink position with respect to those relay nodes to make the network more energy efficient. The relay nodes communicate with the sink instead of the sensor nodes. Tests show that this approach can save at least 40% of the energy and prolong the network lifetime.

关键词： wireless sensor network lifetime sensor node relay node particle swarm optimization sink

A Systematic Review Towards Big Data Analytics in Social Media

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Big Data Mining and Analytics 2022年第3期5卷 228-244页

作者： md.Saifur rahman Hassan Reza School of Electrical Engineering and Computer Science University of North DakotaGrand ForksND 58202USA

The recent advancement in internet 2.0 creates a scope to connect people worldwide using society 2.0 and web 2.0 *** new era allows the consumer to directly connect with other individuals,business corporations,and the *** are open to sharing opinions,views,and ideas on any topic in different formats out *** creates the opportunity to make the"Big Social Data"handy by implementing machine learning approaches and social data *** study offers an overview of recent works in social media,data science,and machine learning to gain a wide perspective on social media big data *** explain why social media data are significant elements of the improved data-driven decision-making *** propose and build the"Sunflower Model of Big Data"to define big data and bring it up to date with technology by combining 5 V’s and 10 *** discover the top ten social data analytics to work in the domain of social media platforms.A comprehensive list of relevant statistical/machine learning methods to implement each of these big data analytics is discussed in this work."Text Analytics"is the most used analytics in social data analysis to *** create a taxonomy on social media analytics to meet the need and provide a clear ***,techniques,and supporting data type are also discussed in this research *** a result,researchers will have an easier time deciding which social data analytics would best suit their needs.

关键词： big data social media big data analytics social media analytics text analytics image analytics audio analytics video analytics predictive analytics descriptive analytics prescriptive analytics diagnostic analytics

Morphological and Genetical Variability among Rhizoctonia solani Isolates Causing Sheath Blight Disease of Rice

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Rice science 2016年第1期23卷 42-50页

作者： Zakiah rahman MONI md Ansar ALI md Shahidul ALAM md Asif rahman md Rejwan BHUIYAN md Salim MIAN Khandakar md IFTEKHARUDDAULA md Abdul LATIF Mohammad Ashik Iqbal KHAN Plant Breeding Division Bangladesh Rice Research Institute Director Research Bangladesh Rice Research Institute Department of Botany Rajshahi University Department of Genetics and Plant Breeding Bangabandhu Sheikh Mujibur Rahman Agricultural University Plant Pathology Division Bangladesh Rice Research Institute

Eighteen isolates of Rhizoctonia solani collected from infected rice plants in four different locations of Bangladesh were studied by using morphological characters and molecular markers. Anastomosis study with a reference isolate confirmed that all the isolates belonged to R. solani. Significant variation was observed in sclerotial size, shape and distribution. Un-weighted pair group method with arithmetic mean dendrogram constructed based on the Gower＇s general similarity coefficient showed that these isolates were grouped into four clusters at the 0.68 similarity coefficent according to morphological characters. Cluster I was a major cluster consisting of 13 isolates, while clusters Ⅱ to Ⅳ consisted of 1 or 2 isolates. Analyses by variable number of tandem repeat and amplified fragment length polymorphism markers showed that the isolates were grouped into five and three clusters at a similarity coefficient of 0.64 and 0.69, respectively. Although most of the variability was found between isolates from different regions as expected, significant variation was observed within the isolates collected from similar agro-ecological regions. Our results suggest the presence of different races of R. solani within the same local geographic regions.

关键词： rice Rhizoctonia solani fungal variability molecular marker morphological character

An Asset-Based Approach to Mitigate Zero-Day Ransomware Attacks

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Computers, Materials & Continua 2022年第11期73卷 3003-3020页

作者： Farag Azzedin Husam Suwad md Mahfuzur rahman Information&Computer Science Department KFUPMDhahranKSA

This article presents an asset-based security system where security practitioners build their systems based on information they own and not solicited by observing attackers’*** security solutions rely on information coming from *** are current monitoring and detection security solutions such as intrusion prevention/detection systems and *** article envisions creating an imbalance between attackers and defenders in favor of *** such,we are proposing to flip the security game such that it will be led by defenders and not *** are proposing a security system that does not observe the behavior of the *** the contrary,we draw,plan,and follow up our own protection strategy regardless of the attack *** objective of our security system is to protect assets rather than protect against *** machine introspection is used to intercept,inspect,and analyze system *** system callbased approach is utilized to detect zero-day ransomware *** core idea is to take advantage of Xen and DRAKVUF for system call interception,and leverage system calls to detect illegal operations towards identified critical *** utilize our vision by proposing an asset-based approach to mitigate zero-day ransomware *** obtained results are promising and indicate that our prototype will achieve its goals.

关键词： Zero-day attacks ransomware system calls virtual machine introspection

Impact of taxes on the 2030 Agenda for Sustainable Development:Evidence from Organization for Economic Cooperation and Development(OECD)countries

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区域可持续发展(英文) 2023年第3期4卷 235-248页

作者： md Mominur rahman Department of Business Administration Northern University BangladeshDhaka1230Bangladesh

Multiple ecological and socioeconomic problems have occurred worldwide,raising the awareness of *** study aims to examine the impact of taxes on Sustainable Development Goals(SDGs)in the context of Organization for Economic Co-operation and Development(OECD)*** research used effective average tax(EAT),tax on personal income(TPI),tax on corporate profits(TCP),and tax on goods and services(TGS)as the variables of taxes,and employed secondary data from 38 OECD countries covering 2000–*** study also used Breusch-Pagan Lagrange Multiplier(LM),Pesaran Scaled LM,Bias-Corrected Scaled LM,and Pesaran Cross-sectional dependence(CSD)tests to analyze the existence of crosssectional ***,we established the stationarity of variables through second-generation panel unit root tests(Cross-sectional Augmented Dickey-Fuller(CADF)and Cross-sectional Im,Pesaran,and Shin(CIPS)),and confirmed the long-run cointegration of the variables by using secondgeneration panel cointegration test(Westerlund cointegration test).The results showed that EAT,TPI,TCP,and TGS are positively associated with ***,the change in TPI has a smaller effect on SDGs than the change in EAT or TCP or *** result of panel causality indicated that EAT,TPI,and TGS have a unidirectional causal relationship with *** study also found that TCP has a bi-directional causal relationship with ***,the finding indicated that the OECD countries need to focus on tax policies to achieve the 2030 Agenda for Sustainable *** study is based on the theory of optimal taxation(TOT),which suggests that tax systems should be designed to maximize social ***,we suggests the importance of taking a comprehensive approach for the managers and policy-makers when analyzing the impact of taxes on SDGs.

关键词： Sustainable Development Goals(SDGs) Organization for Economic Cooperation and Development(OECD)countries Effective average tax(EAT) Tax on personal income(TPI) Tax on corporate profits(TCP) Tax on goods and services(TGS)