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Enhancement of coercivity,permeability,and dielectric properties of Co_(0.2)Zn_(0.3)Ni_(0.5)Eu_(x)Fe_(2-x)O_(4) ferrites for memory and high frequency devices

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Journal of Rare Earths 2024年第6期42卷 1128-1135,I0005页

作者： I.Sardar m.D.hossain m.S.Sikder m.N.I.Khan m.R.Rahman Physics Discipline Khulna UniversityKhulna9208Bangladesh Department of Physics Khulna University of Engineering&TechnologyKhulna9203Bangladesh Department ofComputer Science and Engineering Northern University of Business&Technology KhulnaKhulna9100Bangladesh material Science Division Atomic Energy CentreDhaka1000Bangladesh

Spinel cubic ferrites have huge applications in me mory and high frequency *** the improvement of these modern devices,the magnetic coercivity,permeability,and dielectric properties of a ferrite are the important *** article focuses on improving the magnetic coercivity,magnetic permeability,and dielectric properties of Co_(0.2)Zn_(0.3)Ni_(0.5)Eu_(x)Fe_(2-x)O_(4) ferrites,where x=0.00,0.06,and *** X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),field emission scanning electron microscopy(FESEm),energy dispersive X-ray(EDX),vibrating sample magnetometer(VSm),and an impedance analyzer were used to characterize the structural,magnetic,and dielectric properties of the *** XRD patterns indicate the formation of spinel cubic structure of the samples with a secondary peak(EuFeO_(3))for Eu doped *** densities and porosities of the samples follow an inverse trend,where the doped samples’lattice parameters are increased with the increment of rare earth Eu *** FTIR analysis also proves the spinel cubic phase of the *** average grain size of the ferrites is obtained via FESEm images,and it is increased from 121 to 198 *** analysis confirms that doping of the Eu content also changes other hysteresis loop properties of Co_(0.2)Zn_(0.3)Ni_(0.5)Eu_(x)Fe_(2-x)O_(4) ***,the coercivity of the Eu doped samples is greater than that of the mother alloy(x=0.00).The EDX study shows that there is no impurity contamination in the *** permeability and dielectric measurements show an improved quality factor of the Eu-doped samples with low magnetic and dielectric *** dependent resistivity and impedance analysis also show the improved *** the observed properties of the samples,all the investigated ferrites might be strong candidates for potential applications in memory devices,magnetic sensors,and high frequency applications.

关键词： Ferrites Raree arths Coercivity Permeability EDX Resistivity

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microalgae cultivation in photobioreactors: sustainable solutions for a greener future

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Green Chemical Engineering 2024年第4期5卷 418-439页

作者： Shaikh Abdur Razzak Khairul Bahar K.m.Oajedul Islam Abdul Khaleel Haniffa mohammed Omar Faruque S.m.Zakir hossain mohammad m.hossain Chemical Engineering Department King Fahd University of Petroleum and Minerals Center for Refining and Advanced Chemicals King Fahd University of Petroleum & Minerals Department of Chemical Engineering University of Bahrain

microalgae cultivation in photobioreactors（PBRs） has emerged as a promising and sustainable approach to address various environmental and energy challenges, offering a multitude of benefits across diverse *** developments in microalgae cultivation in photobioreactors have contributed substantially to the development and optimization of sustainable bioprocesses. This review presents a comprehensive analysis of recent innovations and breakthroughs in the field of microalgae cultivation, with a specific focus on their application in photobioreactors, aimed at paving the way for a greener future. This study in-depth examines the advantages of microalgae cultivation in photobioreactors, concentrating on its effectiveness in wastewater treatment, CO2bioremediation, and the production of biofuels and high-value products. The review evaluates the effects of light,solar irradiation, temperature, nitrogen and phosphorus concentrations in culture media, CO2concentrations, and pH on microalgae growth performance, including specific growth and biomass productivity. The study also examines open systems like unstirred ponds, raceway ponds, and circular ponds and closed systems like horizontal tubular, vertical bubble-column, airlift, flat panel, and plastic-bag photobioreactors, comparing their pros and cons. To optimize microalgae cultivation, key factors in photobioreactor design, including photosynthetic efficiencies, light/dark（L/D） cycles, CO2concentrations, mass transfer, hydrodynamics behavior, and p H, are extensively investigated. In addition, the review outlines recent developments in large-scale photobioreactors and highlights the challenges and opportunities associated with photobioreactor scale-up and design parameter optimization, including genetic engineering and economic feasibility. This article is a vital resource for researchers, engineers, and industry professionals seeking sustainable bioprocesses and the application of microalgae-based technol

关键词： microalgae biomass CO 2 biofixation Wastewater treatment Biofuel Photobioreactors

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RBFK cipher:a randomized butterfly architecture‑based lightweight block cipher for IoT devices in the edge computing environment

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网络空间安全科学与技术(英文) 2023年第3期6卷 18-36页

作者： Sohel Rana m.rubaiyat hossain m.ndal Joarder Kamruzzaman Institute of Information and Communication Technology Bangladesh University of Engineering and TechnologyDhakaBangladesh Centre for Smart Analytics Federation University AustraliaGippslandVIC 3842Australia

Internet security has become a major concern with the growing use of the Internet of Things(IoT)and edge computing *** though data processing is handled by the edge server,sensitive data is generated and stored by the IoT devices,which are subject to *** most IoT devices have limited resources,standard security algorithms such as AES,DES,and RSA hamper their ability to run *** this paper,a lightweight symmetric key cipher termed randomized butterfly architecture of fast Fourier transform for key(RBFK)cipher is proposed for resource-constrained IoT devices in the edge computing *** butterfly architecture is used in the key scheduling system to produce strong round keys for five rounds of the encryption *** RBFK cipher has two key sizes:64 and 128 bits,with a block size of 64 *** RBFK ciphers have a larger avalanche effect due to the butterfly architecture ensuring strong *** proposed cipher satisfies the Shannon characteristics of confusion and *** memory usage and execution cycle of the RBFK cipher are assessed using the fair evaluation of the lightweight cryptographic systems(FELICS)*** proposed ciphers were also implemented using mATLAB 2021a to test key sensitivity by analyzing the histogram,correlation graph,and entropy of encrypted and decrypted *** the RBFK ciphers with minimal computational complexity provide better security than recently proposed competing ciphers,these are suitable for IoT devices in an edge computing environment.

关键词： Avalanche effects Block ciphers Butterfly architecture Edge computing FELICS IoT Lightweight cryptosystems mATLAB

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machine learning-based multi-objective optimization and thermal assessment of supercritical CO_(2) Rankine cycles for gas turbine waste heat recovery

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Energy and AI 2024年第2期16卷 363-384页

作者： Asif Iqbal Turja Ishtiak Ahmed Khan Sabbir Rahman Ashraf mustakim mohammad Ishraq hossain m monjurul Ehsan Yasin Khan Department of mechanical and Production Engineering(mPE) Islamic University of Technology(IUT)Board BazarGazipur1704Bangladesh

Technologies for utilizing waste heat for power generation have attracted significant attention in recent years due to their potential to enhance energy efficiency and reduce greenhouse gas *** research focuses on the comparative and optimization analysis of three supercritical carbon dioxide(sCO_(2))Rankine cycles(simple,cascade,and split)for gas turbine waste heat *** study begins with parametric analysis,investigating the significant effects of key variables,including turbine inlet temperature,condenser inlet temperature,and pinch point temperature,on the thermal performance of advanced sCO_(2) power *** identify the most efficient cycle configuration,a multi-objective optimization approach is *** approach combines a Genetic Algorithm with machine learning regression models(Random Forest,XGBoost,Artificial Neural Network,Ridge Regression,and K-Nearest Neighbors)to predict cycle performance using a dataset extracted from cycle *** decision-making process for determining the optimal cycle configuration is facilitated by the TOPSIS(technique for order of preference by similarity to the ideal solution)*** study's major findings reveal that the split cycle outperforms the simple and cascade configurations in terms of power generation across various operating *** optimized split cycle not only demonstrates superior power output but also exhibits enhanced net power output,heat recovery,system and exergy efficiency of 7.99 mW,76.17%,26.86%and 57.96%,respectively,making it a promising choice for waste heat recovery *** research has the potential to contribute to the advancement and widespread adoption of waste heat recovery in energy technologies boosting system efficiency and economic *** provides a new perspective for future research,contributing to the improvement of energy generation infrastructure.

关键词： Supercritical co2 Rankine cycle Waste heat recovery Gas turbine Thermodynamic analysis machine Learning Optimization

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Exploring the electromagnetic shielding behavior of lanthanum doped calcium nanoferrites

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Journal of Rare Earths 2024年第11期42卷 2128-2136页

作者： E.Ahilandeswari K.Sakthipandi R.Rajesh Kanna G.Rajkumar B.Ganesh Babu S.Arunmetha Aslam hossain P.Sakthivel V.Rajendran m.Srinidhi Raghavan Department of Physics SRM TRP Engineering College Department of Electronics and Communication Engineering M. Kumarasamy College of Engineering Department of Physics Easwari Engineering College Department of mechanical Engineering SRM TRP Engineering College Centre for Advanced Energy Studies Department of Electronics and Communication EngineeringKoneru Lakshmaiah Education Foundation Smart materials Research Institute Southern Federal University Centre for materials Science Department of PhysicsScience and HumanitiesFaculty of EngineeringKarpagam Academy of Higher Education Centre for Nanotechnology Academy of Maritime Education and Training (Deemed to be University) Department of Chemistry and Centre for Nano-materials and Displays B.M.S. College of Engineering

The present study focuses on the synthesis and characterization of lanthanum(La3+)-doped calcium nanoferrites(CaLaxFe2-xO4:x=0.025,0.050,0.075 and 0.100) using the sonochemical *** techniques were employed to analyze the effect of La3+infusion,Raman spectroscopy confirms the presence of active A1g,T2gand Egmodes in the CaLaxFe2-xO4nanoferrite,indicating the formation of an active ferrite *** introduction of La3+doping results in a significant increase in the band gap energy,rendering the nanoferrites insulating（3.23-3,57 eV）.At higher frequencies,the impedance studies reveal minimal losses and better AC conductivity,pointing to improved dielectric *** higher frequencies,the Q-factor of La-doped calcium nanoferrites shows lower electromagnetic *** m-H curve exhibits ferromagnetic behavior,with La3+-doped calcium nano ferrites displaying a saturation magnetization ranging from 12.72 to 18.10 emu/*** incorporation of La3+also induces enhanced electrical polarization,leading to notable dielectric loss and increased absorption of electromagnetic ***,these CaLaxFe2-xO4nanoferrites demonstrate potential as effective microwave absorbers across a wide frequency range,with significant shielding absorption observed at 8.8-9.1 GHz.

关键词： Dielectric magnetism microwave absorption Nanoferrites Rare earths Structural properties

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Predicting the Stitch Density of Finished Fabrics Using Weft Blended Grey Knit Fabrics

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Journal of Textile Science and Technology 2024年第3期10卷 51-63页

作者： Kazi md. Elias mohammad Obaidur Rahman H. m. Zakir hossain Department of Physics Jahangirnagar University Savar Bangladesh Jute Textile Wing Bangladesh Jute Research Institute Dhaka Bangladesh

Stitch density is one of the critical quality parameters of knit fabrics. This parameter is closely related to other physical quality parameters like fabric weight, fabric tightness factor, fiber types, blend ratio, yarn diameter and linear density, and fabric structure. Selecting stitch density (wales per inch, course per inch) is essential to getting the appropriate fabric weight and desired quality. Usually, no rules or assumptions exist to get the desired stitch density in the finished fabric stage. Fifteen types of blended knit fabrics were prepared to conduct the study. The varying percentages of cotton, polyester, and elastane are incorporated in the blends. Regression analysis and regression ANOVA tests were done to predict the stitch density of finished fabrics. A suitable regression equation is established to get the desired results. The study also found that the stitch density value in the finished stage fabric decreases by approximately 15% compared to the stitch density in the grey fabric stage. This study will help the fabric manufacturers get the finished fabric stitch density in advance by utilizing the grey fabric stitch density data set. The author expects this research to benefit the knitting and dyeing industry, new researchers, and advanced researchers.

关键词： Wales per Inch Course per Inch Stitch Density Blended Knit Fabric

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Beyond Stitches: Analysis of Disease Burden in a Bangladeshi RmG Factory

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Health 2024年第7期16卷 688-702页

作者： mariam Zaman Tayeb Ahmmed Nabila Binte hossain S. m. Raysul Haque Ariful Islam Joarder Kamran ul Baset Department of Procurement SM Group Dhaka Bangladesh Department of Neurosurgery Bangabandhu Sheikh Mujib Medical University (BSMMU) Dhaka Bangladesh Department of Public Health Independent University Bangladesh (IUB) Dhaka Bangladesh Department of Cardiology Bangabandhu Sheikh Mujib Medical University (BSMMU) Dhaka Bangladesh

Introduction: Bangladesh has experienced remarkable growth in RmG over the past 25 years. With the knitwear industry providing more than 4 million direct jobs, providing better occupational health and safety of workers remains a challenge. Aim of the study: The aim of the study was to analyze the disease burden of a RmG factory, and to highlight occupational health risks. methods: A cross-sectional study design was employed for this analysis. A 17-month data entry (January 2020 - may 2021) was gathered from the factory in-house clinic. The socio-demographic and clinical diagnosis entries of 8421 entries were analyzed. Result: The population of the factory workers is 5370, where 40% (2148) are female workers and 60% (3222) are male workers. The mean age of respondents is 30 years, with a SD of ±7 years. Among the chief complaints, the most common was vomiting (14%;2262) fever (14%;2247), runny nose (11%;1842), cough (9%;1465), and loose motion (8%;1364). In the diagnosis categories, gastrointestinal diseases were more predominantly diagnosed (35%;2978), followed by viral fever (21%;1772), neurological diseases (16.5%;1389) and musculoskeletal disorders (9%;768). The average cost of medicine for each respondent is BDT 36. The factory covered costs of all medication for 99% (8380) of respondents. Only 0.5% (37) was referred to a tertiary hospital for further evaluation. Conclusion: Garments workers suffer mostly from long-term occupational health hazards. Factory owners and policy makers can contribute in various ways to improving primary healthcare options for workers.

关键词： RmG Disease Burden Work Related Disease Communicable Disease Occupational Safety

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Impact of Action Observation Therapy along with Usual Physiotherapy Intervention of Individual with Alzheimer’s Disease

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Advances in Alzheimer's Disease 2024年第1期13卷 1-10页

作者： Zahid Bin Sultan Nahid Faruq Ahmed Tuhin Ahammed md Kutub Uddin md Sirazul Islam S m maruf hossain Sajib md Rafiqul Islam Department of Physiotherapy Saic College of Medical Science and Technology Mirpur Bangladesh Department of Physiotherapy Centre for the Rehabilitation of the Paralysed (CRP) Savar Bangladesh Department of Physiotherapy Centre for the Rehabilitation of the Paralysed (CRP) Mymensingh Bangladesh Department of Physiotherapy Centre for the Rehabilitation of the Paralysed (CRP) Mirpur Bangladesh Department of Physiotherapy State College of Health Sciences Dhaka Bangladesh

Alzheimer’s disease (AD) is a neurodegenerative disorder characterized by cognitive impairments in the initial stage, which lead to severe cognitive dysfunction in the later stage. Action observation therapy (AOT) is a multisensory cognitive rehabilitation technique where the patient initially observes the actions and then tries to perform. The study aimed to examine the impact of AOT along with usual physiotherapy interventions to reduce depression, improve cognition and balance of a patient with AD. A 67 years old patient with AD was selected for this study because the patient has been suffering from depression, dementia, and physical dysfunction along with some other health conditions like diabetes and hypertension. Before starting intervention, a baseline assessment was done through the Beck Depression Inventory (BDI) tool, the mini-Cog Scale, and the Berg Balance Scale (BBS). The patient received 12 sessions of AOT along with usual physiotherapy interventions thrice a week for four weeks, which included 45 minutes of each session. After four weeks of intervention, the patient demonstrated significant improvement in depression, cognition, and balance, whereas the BDI score declined from moderate 21/63 to mild 15/63 level of depression. The mini-Cog score improved from 2/5 to 4/5, and the BBS score increased from 18/56 to 37/56. It is concluded that AOT along with usual physiotherapy intervention helps to reduce depression, improve cognition and balance of people with AD.

关键词： Alzheimer’s Disease Action Observation Therapy Physiotherapy Intervention

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Comparative study of mo2Ga2C with superconducting mAX phase mo2GaC： First-principles calculations

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Chinese Physics B 2017年第3期26卷 297-302页

作者： m A Ali m R Khatun NJahan m m hossain Department of Physics Chittagong University of Engineering and Technology Chittagong 4349 Bangladesh Department of Physics University of Rajshahi Rajshahi 6205 Bangladesh

The structural, electronic, optical and thermodynamic properties of mo2Ga2C are investigated using density func- tional theory （DFT） within the generalized gradient approximation （GGA）. The optimized crystal structure is obtained and the lattice parameters are compared with available experimental data. The electronic density of states （DOS） is calculated and analyzed. The metallic behavior for the compound is confirmed and the value of DOS at Fermi level is 4.2 states per unit cell per eV. Technologically important optical parameters （e.g., dielectric function, refractive index, absorption coefficient, photo conductivity, reflectivity, and loss function） are calculated for the first time. The study of dielectric constant （ε1） indicates the Drude-like behavior. The absorption and conductivity spectra suggest that the compound is metallic. The reflectance spectrum shows that this compound has the potential to be used as a solar reflector. The thermodynamic properties such as the temperature and pressure dependent bulk modulus, Debye temperature, specific heats, and thermal expansion coefficient of mo2Ga2C mAX phase are derived from the quasi-harmonic Debye model with phononic effect also for the first time. Analysis of Tc expression using available parameter values （DOS, Debye temperature, atomic mass, etc.） suggests that the compound is less likely to be superconductor.

关键词： first-principles calculations density of states (DOS) optical properties thermodynamic properties

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Non-Newtonian effect on natural convection flow over cylinder of elliptic cross section

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Applied mathematics and mechanics(English Edition) 2020年第2期41卷 361-382页

作者： P.NAG m.m.mOLLA m.A.hossain Department of mathematics and Physics North South UniversityDhaka 1229Bangladesh Center for Applied Scientific Computing(CASC) North South UniversityDhaka 1229Bangladesh Department of mathematics University of DhakaDhaka 1000Bangladesh

The non-Newtonian effect in the boundary layer flow over a horizontal elliptical cylinder is investigated numerically. A modified power-law viscosity model is used to correlate the non-Newtonian characteristics of the fluid flow. For natural convectionflows, the surface of the cylinder is maintained by the uniform surface temperature(UST)or the uniform heat flux(UHF) condition. The governing equations corresponding to theflow are first transformed into a dimensionless non-similar form using suitable transformations. The resulting equations are solved numerically by an efficient finite difference scheme. The numerical results are presented for the skin friction coefficient and the local Nusselt number with the eccentric angle for different values of the power-law index n. The local skin friction coefficient and the local Nusselt number are found to be higher and lower, respectively, for the shear thickening fluids(n > 1) than the other fluids(n≤1).The effects of different elliptical configurations on the average Nusselt number are also presented and discussed for both conditions of the surface temperature.

关键词： non-Newtonian fluid free convection boundary layer elliptical cylinder

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