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Effect of 3 mol% Yttria Stabilized Zirconia Addition on Structural and Mechanical Properties of Alumina-Zirconia Composites

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Materials Sciences and Applications 2017年第7期8卷 584-602页

作者： M. A. Gafur md. saifur rahman sarker md. Zahangir Alam M. R. Qadir PP & PDC BCSIR Dhaka Bangladesh Department of Chemistry Kurigram Govt. College Kurigram Rangpur Bangladesh Department of ACCE Dhaka University Dhaka Bangladesh

Alumina-Zirconia (Al2O3-ZrO2) composites especially Zirconia Toughened Alumina (ZTA) shows better mechanical properties over alumina. Al2O3-ZrO2 composites were prepared by powder compaction method varying 3 mol% yttria stabilized zirconia (3Y-ZrO2) content from 0 to 20 vol% using small amount of MgO as sintering aid. The composites were sintered for two hours in air at 1580°C. At this temperature maximum density was achieved 99.31% of theoretical density for composite containing 20 vol% 3Y-ZrO2. Density measurement of sintered composites was carried out using Archimedes’s method. Hardness and fracture toughness measurement was carried out using Vickers indentation. Phase content and t-ZrO2 retention were detected by means of X-ray diffraction (XRD). Microstructure of the composites and grain size of alumina and zirconia was determined by Scanning Electron Microscopic (SEM) analysis. Maximum microhardness (17.46 GPa) was achieved for composite containing 5 vol% ZrO2 and maximum flexural strength (684.32 MPa) and fracture toughness (10.33 MPam0.5) was achieved for composite containing 20 vol% of 3Y-ZrO2. The aim of the present work is to investigate the optimum 3Y-ZrO2 content for obtaining maximum density, microhardness, flexural strength and fracture toughness of Al2O3-ZrO2 composites.

关键词： Alumina-Zirconia Composites Sintering t-ZrO2 Retention Grain Size

Frame Length Dependency for Fundamental Frequency Extraction in Noisy Speech

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Journal of Signal and Information Processing 2024年第1期15卷 1-17页

作者： md. saifur rahman Any Chowdury Nargis Parvin Arpita Saha Moinur rahman Department of Information and Communication Technology Comilla University Cumilla Bangladesh Department of Computer Science and Engineering Bangladesh Army International University of Science and Technology (BAIUST) Cumilla Bangladesh Department of Information Technology University of Information Technology and Sciences (UITS) Dhaka Bangladesh

The fundamental frequency plays a significant part in understanding and perceiving the pitch of a sound. The pitch is a fundamental attribute employed in numerous speech-related works. For fundamental frequency extraction, several algorithms have been developed which one to use relies on the signal’s characteristics and the surrounding noise. Thus, the algorithm’s noise resistance becomes more critical than ever for precise fundamental frequency estimation. Nonetheless, numerous state-of-the-art algorithms face struggles in achieving satisfying outcomes when confronted with speech recordings that are noisy with low signal-to-noise ratio (SNR) values. Also, most of the recent techniques utilize different frame lengths for pitch extraction. From this point of view, This research considers different frame lengths on male and female speech signals for fundamental frequency extraction. Also, analyze the frame length dependency on the speech signal analytically to understand which frame length is more suitable and effective for male and female speech signals specifically. For the validation of our idea, we have utilized the conventional autocorrelation function (ACF), and state-of-the-art method BaNa. This study puts out a potent idea that will work better for speech processing applications in noisy speech. From experimental results, the proposed idea represents which frame length is more appropriate for male and female speech signals in noisy environments.

关键词： Pitch Estimation Fundamental Frequency BaNa ACF Frame Length

Adequate Closed Form Wave Solutions to the Generalized KdV Equation in Mathematical Physics

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Journal of Applied Mathematics and Physics 2024年第6期12卷 2069-2082页

作者： md. Munnu Miah md. Al Amin Meia md. Matiur rahman sarker Ahammodullah Hasan Department of Mathematics Islamic University Kushtia Bangladesh Department of Mathematics Government Titumir College Dhaka Bangladesh Department of Pharmacy University of Asia Pacific Dhaka Bangladesh

In this paper, we consider the generalized Korteweg-de-Vries (KdV) equations which are remarkable models of the water waves mechanics, the shallow water waves, the quantum mechanics, the ion acoustic waves in plasma, the electro-hydro-dynamical model for local electric field, signal processing waves through optical fibers, etc. We determine the useful and further general exact traveling wave solutions of the above mentioned NLDEs by applying the exp(−τ(ξ))-expansion method by aid of traveling wave transformations. Furthermore, we explain the physical significance of the obtained solutions of its definite values of the involved parameters with graphic representations in order to know the physical phenomena. Finally, we show that the exp(−τ(ξ))-expansion method is convenient, powerful, straightforward and provide more general solutions and can be helping to examine vast amount of travelling wave solutions to the other different kinds of NLDEs.

关键词： The Generalized KdV Equation The exp(-τ(ξ)) -Expansion Method Travelling Wave Solitary Wave

Rural Resilience: A Comprehensive Study on Water Supply, Sanitation, Disease Patterns, and Hygiene Practices in Munshiganj, Bangladesh

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Journal of Environmental Protection 2024年第1期15卷 63-75页

作者： Jubayer Hoque Rifat Islam md. Mustafizur rahman md. Golam Rabbani md. Selim Reja saifur rahman Soykat Saim Raiyan md. Shafiqul Ahsan Emon Sakil Khan Department of Environmental Science and Disaster Management Bangabandhu Sheikh Mujibur Rahman Science and Technology University Gopalgnj Bangladesh Department of Political Science Bangabandhu Sheikh Mujibur Rahman Science and Technology University GopalgnjBangladesh Department of Statistics Bangabandhu Sheikh Mujibur Rahman Science and Technology University Gopalgnj Bangladesh

This research project investigates the current status of water supply, sanitation, and hygiene practices in Munshiganj District, Bangladesh. Data collection involved a structured questionnaire and a reconnaissance survey. Findings reveal that 30% of individuals rely on surface water (hand-tube wells, rivers, and ponds), prioritized as canal > river > pond, while 70% depend on groundwater (subterranean electric motor, deep tube-well). Drinking water is generally sufficient, with 95% reporting adequacy throughout the year. About 45% use hand tube-well water, 28% use deep tube-well water, and 11% use supply tap water for various purposes. Bathing trends include underground water through electric motor > pond > hand tube-well water > river, while for cooking, the order is underground water through electric motor > pond > hand tube-well water > river. Toilet water supply ranks as supply tap water > hand tube-well water > deep tube-well water. Although sanitation awareness is high, some lack knowledge of good hygiene practices. After defecating, handwashing methods include soap, ash, soil, or water. Children’s waste disposal varies, with some discarding it in open areas. Approximately 40% suffer from diseases like Diarrhoea due to unsafe water, primarily affecting children and elders. Training exists, but a significant portion lacks sanitation education. Dry skin or exposure to cold water may cause temporary irritation. Local government involvement in sanitation efforts is less active compared to non-governmental organizations. Results emphasize the need to enhance community awareness of safe water supplies and sanitation practices. .

关键词： Water Supply Sanitation Practices Hygiene Awareness Groundwater Dependency Community Health Intervention

Credit Card Fraud Detection Using Machine Learning Techniques

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Journal of Computer and Communications 2024年第6期12卷 1-11页

作者： Ananya sarker Must. Asma Yasmin md. Atikur rahman md. Harun Or Rashid Bristi Rani Roy Department of Computer Science and Engineering Bangladesh Army University of Engineering & Technology (BAUET) Natore Bangladesh

Credit card companies must be able to identify fraudulent credit card transactions so that clients are not charged for items they did not purchase. Previously, many machine learning approaches and classifiers were used to detect fraudulent transactions. However, because fraud patterns are always changing, it is becoming increasingly vital to investigate new frauds and develop the model based on the new patterns. The purpose of this research is to create a machine learning classifier that not only detects fraud but also detects legitimate transactions. As a result, the model should have excellent accuracy, precision, recall, and f1-score. As a result, we began with a large dataset in this study and used four machine learning classifiers: Support Vector Machine (SVM), Decision Tree, Naïve Bayes, and Random Forest. The random forest classifier scored 99.96% overall accuracy with the best precision, recall, f1-score, and Matthews correlation coefficient in the experiments.

关键词： Support Vector Machine Decision Tree Nave Bayes Random Forest Matthews Correlation

A Critical Review of Community Resilience Building Framework: Contexts of Climate Change and Disasters in Bangladesh

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Journal of Geoscience and Environment Protection 2024年第9期12卷 315-334页

作者： Abdul Alim Shaikh Mousumi Halder Muhammad Ramzan Ali Ruhul Amin md.saifur rahman md. Kamruzzaman Khulna University Khulna Bangladesh Climate Change Program Christian Commission for Development in Bangladesh (CCDB) Dhaka Bangladesh International Rescue Committee-UK Coxs Bazar Bangladesh Tropical and International Forestry Technical University Dresden Cotta Bau Pienner Strae 7 01737 Tharandt Germany Forestry and Wood Technology Discipline Khulna University Khulna Bangladesh

The concept of community resilience in the contexts of climate change and disasters draws increasing attention and interest from practitioners and researchers in recent development discourse. This paper provides a critical review of six selected frameworks of community resilience building operationalized in Bangladesh over the span of years. In other words, this study aims to contribute to the understanding of resilience through a systematic analysis of the dimensions and indicators of community resilience frameworks. The analysis shows that comprehensive and effective community resilience frameworks should incorporate the missing components linked to fundamental elements of good governance, economic growth, environmental sustainability, social transformation, and capacity development. The paper concludes by highlighting a few other areas of grave concern that need more appropriate attention, considering the severe threats posed by climate change and natural disasters in line with sustainable development goals. Finally, this study recommends further research regarding the effectiveness of these frameworks in different climatic and disaster contexts that can lead the concept into a new dimension of community resilience and sustainability.

关键词： Community Resilience Resilience Building Framework Resilience Indicators Climate Change Disaster Bangladesh

Effect of Exchange-Correlation Functional on the Structural, Mechanical, and Optoelectronic Properties of Orthorhombic RbSrBr3 Perovskite

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Materials Sciences and Applications 2024年第6期15卷 137-154页

作者： Fatema Najrin Rabeya Bakar Sarna md. Alamin sarker Budrun Neher md. Mahbubur rahman Bhuiyan Farid Ahmed Department of Physics Jahangirnagar University Dhaka Bangladesh Department of Electrical and Electronics Engineering Green University of Bangladesh Purbachal American City Kanchan Rupganj Narayanganj-1461 Dhaka Bangladesh

In the present study, the effect of the exchange-correlation functional on the structural, mechanical, and optoelectronic properties of orthorhombic RbSrBr3 perovskite has been investigated using various functionals in Density Functional Theory (DFT) with the CASTEP code. The optimized lattice parameters are quite similar for all the functionals. The electronic properties have shown that RbSrBr3 perovskite is a wide direct band gap compound with a band gap energy ranging from 4.296 eV to 4.494 eV for all the functionals. The mechanical parameters like elastic constants, Young’s modulus, Shear modulus, Poisson’s ratio, Pugh’s ratio, and an anisotropic factor reveal that the RbSrBr3 perovskite has ductile behavior and an anisotropic nature which signifies the mechanical stability of the compound. The Debye temperature might withstand lattice vibration heat. High absorption coefficient (>104 cm−1), high optical conductivity, and very low reflectivity have been found in the RbSrBr3 perovskite for all functions. The computed findings on the RbSrBr3 perovskite suggested that the presented studied material is potentially applicable for photodetector and optoelectronic devices.

关键词： Density Functional Theory Mechanical Properties Photodetector Ductility Anisotropic Factor

The link between intracellular calcium signaling and exosomal PD-L1 in cancer progression and immunotherapy

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Genes & Diseases 2024年第1期11卷 321-334页

作者： md.Rakibul Alam md.Mizanur rahman Zhiguo Li Department of Toxicology and Cancer Biology College of MedicineUniversity of KentuckyLexingtonKY 40506USA Department of Medicine(Nephrology) Faculty of Medicine and DentistryUniversity of AlbertaEdmontonAlberta T6E2H7Canada

Exosomes are small membrane vesicles containing microRNA,RNA,DNA fragments,and proteins that are transferred from donor cells to recipient *** cells release exo-somes to reprogram the factors associated with the tumor microenvironment(TME)causing tu-mor metastasis and immune *** evidence revealed that cancer cell-derived exosomes carry immune inhibitory molecule program death ligand 1(PD-L1)that binds with re-ceptor program death protein 1(PD-1)and promote tumor progression by escaping immune ***,some FDA-approved monoclonal antibodies are clinicallyused for cancer treatment by blocking PD-1/PD-L1 *** notable treatment outcomes,some pa-tients show poor drug *** PD-L1 plays a vital role in lowering the treatment response,showing resistance to PD-1/PD-L1 blockage therapy through recapitulating the ef-fect of cell surface *** enhance therapeutic response,inhibition of exosomal PD-L1 is *** signaling is the central regulator of tumorigenesis and can regulate exosome biogenesis and secretion by modulating Rab GTPase family and membrane fusion ***-mune checkpoints are also connected with calcium signaling and calcium channel blockers like amlodipine,nifedipine,lercanidipine,diltiazem,and verapamil were also reported to suppress cellular PD-L1 ***,to enhance the PD-1/PD-L1 blockage therapy response,the reduction of exosomal PD-L1 secretion from cancer cells is in our therapeutic *** this review,we proposed a therapeutic strategy by targeting calcium signaling to inhibit the expression of PD-L1-containing exosome levels that could reduce the anti-PD-1/PD-L1 therapy resistance and increase the patient's drug response rate.

关键词： Calcium signaling CD8^(+)T cells Exosomal PD-L1 Exosomes biogenesis Immunosuppression Immunotherapy

Thornthwaite moisture index and depth of suction change under current and future climate‒An Australian study

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第5期16卷 1761-1775页

作者： md.Rajibul Karim Bikash Devkota md.Mizanur rahman Hoang Bao Khoi Nguyen UniSA STEM University of South AustraliaMawson Lakes CampusMawson LakesSouth Australia5095Australia

Climate change is one of the major global challenges and it can have a significant influence on the behaviour and resilience of geotechnical *** changes in moisture content in soil lead to effective stress changes and can be accompanied by significant volume changes in reactive/expansive *** volume change leads to ground movement and can exert additional stresses on structures founded on or within a shallow depth of such *** change is likely to amplify the ground movement potential and the associated problems are likely to *** effect of atmospheric boundary interaction on soil behaviour has often been correlated to Thornthwaite moisture index(TMI).In this study,the long-term weather data and anticipated future projections for various emission scenarios were used to generate a series of TMI maps for *** changes in TMI were then correlated to the depth of suction change(H s),an important input in ground movement *** all climate scenarios considered,reductions in TMI and increases in H s values were observed.A hypothetical design scenario of a footing on expansive soil under current and future climate is *** is observed that a design that might be considered adequate under the current climate scenario,may fail under future scenarios and accommodations should be made in the design for such events.

关键词： Climate change Future prediction Thornthwaite moisture index(TMI) Characteristic surface movement Infrastructure resilience