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Mechanical and corrosion behaviour of hydroxyapatite reinforced Mg-Sn alloy composite by squeeze casting for biomedical applications

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Journal of Magnesium and Alloys 2020年第2期8卷 452-460页

作者： r radha d.Sreekanth School of Mechanical and Building Sciences Vellore Institute of TechnologyChennai 600127India

Magnesium alloys have gained increasing attention for biomedical applications due to their biocompatibility and the ***(HA)is known to be a highly bioactive because of its similar chemical and crystallographic structures to ***,HA is believed to be a potential ceramic material for the fabrication of Mg based composites,to combine the advantages of both Mg and ***,in general,the composites known to be more susceptible to corrosion attack than the matrix ***,in the present work,Sn is used as an alloying element to evaluate its effect on mechanical as well as corrosion properties of Mg/HA *** with 5 wt%HA and Mg-1 wt%Sn-5 wt%HA composites were prepared separately by stir assisted squeeze casting *** phase analysis and microstructure were characterized by X-ray diffraction(Xrd)and scanning electron microscope(SEM)coupled with energy dispersive spectroscopy(EdS)*** properties were evaluated by conducting the compression and micro hardness *** properties of as-cast composites were studied by linear polarization,Tafel and electrochemical impedance spectroscopy(EIS)*** results of both Xrd and SEM-EdS revealed that the main constitutional phases of as-cast Mg/HA composites were a-Mg and HA whereas,in Mg-Sn/HA composites,the phase Mg^Sn was observed along with fine distribution of HA *** both the cases,no interfacial reactions *** yield strength,ultimate compression strength and hardness were found to be increased with the addition of Sn in Mg/HA ***,the addition of Sn also played an important role in increasing the corrosion resistance of the Mg/HA composites which was attributed the refinement of grain size and the formation of Mg2Sn phase along the grain ***,it was concluded that the addition of Sn improves both mechanical and corrosion properties of Mg/HA composites.

关键词： Magnesium Composite Biomedical Corrosion Squeeze casting

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Electrical and optical properties of lithium borate glasses doped with Nd_2O_3

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Journal of rare Earths 2012年第8期30卷 785-789页

作者： r.S. Gedam d.d. ramteke department of Applied Physics Visvesvaraya National Institute of Technology

Glass series with general formula 25Li2O-（75-x）B2O3-xNd2O3 was prepared by conventional melt quench technique. Electrical and optical characterizations of these glasses were carried out. It was observed that conductivity of glasses decreased and activation energy in- creased with the addition of Nd2O3. The density and refractive index of the glasses increased while optical band gap and radiation length de- creased due to structural changes.

关键词： conductivity density refractive index optical absorption Tauc's plot rare earths

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Luminescence properties of Gd^(3+) containing glasses for ultra-violet(UV) light

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Journal of rare Earths 2014年第5期32卷 389-393页

作者： d.d.ramteke r.S.Gedam department of Applied Physics Visvesvaraya National Institute of Technology

Effect of Gd2O3 addition on optical properties of 27.5 Li2O-72.5 B2O3 glass systems was studied. density, differential thermal analysis （dTA）, optical absorption spectra and luminescence technique were used to characterize the prepared glasses. Emis- sion spectra showed two band 6p7/2→8S7/2 （311.5 nm） and 6p5/2→8S7/2 （305 nm） under the excitation of 274 nm. The intense emission at 311.5 nm suggested that these glasses could be useful as source of narrowband UV light.

关键词： glasses rare earths absorption band gap luminescence UV light

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radiotherapy-customized head immobilization masks:from modeling and analysis to 3d printing

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Nuclear Science and Techniques 2019年第9期30卷 103-118页

作者： M.A.r.Loja d.S.Craveiro L.Vieira E.Sousa J.A.rodrigues r.J.F.Portal CIMOSM Centro de Investigacao em Modelacao e Optimizacao de Sistemas Multifuncionais ISEL IPL Instituto Superior de Engenharia de Lisboa Av. Conselheiro Emidio Navarro 1 1959-007 Lisbon Portugal LAETA IDMEC Instituto Superior Teccnico Universidade de Lisboa Av. Rovisco Pais 1 1049-001 Lisbon Portugal department of Mechanical and Industrial Engineering Faculty of Science and Technology NOVA UNIDEMI Universidade Nova de Lisboa Caparica Portugal H&TrC -Health &Technology research Center ESTeSL - Escola Superior de Tecnologia da Saude de Lisboa Av. D. Joao II Lote 4.69.01 1990-096 Lisbon Portugal Instituto de Biofisica e Engenharia Biomedica Faculdade de Ciencias da Universidade de Lisboa Lisbon Portugal

Immobilization devices may be a valuable aid to ensure the improved effectiveness of radiotherapy treatments where constraining the movements of specific anatomical segments is crucial. This need is also present in other situations, specifically when the superposition of various medical images is required for fine identification and characterization of some pathologies. Because of their structural characteristics, existing head immobilization systems may be claustrophobic and very uncomfortable for patients, during both the modeling and usage stages. Because of this, it is important to minimize all the discomforts related to the mask to alleviate patients’ distress and to simultaneously guarantee and maximize the restraint effectiveness of the mask. In the present work, various head immobilization mask models are proposed based on geometrical information extracted from computerized tomography images and from 3d laser scanning point clouds. These models also consider the corresponding connection to a radiotherapy table, as this connection is easily altered to accommodate various manufacturers’ solutions. A set of materials used in the radiotherapy field is considered to allow the assessment of the stiffness and strength of the masks when submitted to typical loadings.

关键词： Computed tomography 3d laser scanning Geometric modeling Head immobilization devices Stiffness and strength analyses 3d printing

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Effects of Nano-Y_2O_3 and Sintering Parameters on the Fabrication of PM duplex and Ferritic Stainless Steels

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Acta Metallurgica Sinica(English Letters) 2016年第1期29卷 58-71页

作者： r.Shashanka d.Chaira department of Metallurgical and Materials Engineering National Institute of Technology

Here we report the effects of nano-Y203 addition, sintering atmosphere and time during on the fabrication of PM duplex and ferritic stainless steels composites by dual-drive planetary milling of elemental Fe, Cr and Ni powders followed by conventional pressureless sintering. Yttria-free and yttria-dispersed duplex and ferritic stainless steels are fabricated by conventional sintering at 1000, 1200 and 1400 ℃ temperatures under argon atmosphere. In another set of experiment, yttria-free and yttria-dispersed duplex and ferritic stainless steels are consolidated at 1000 ℃ for l h under nitrogen atmosphere to study the effect of sintering atmosphere. It has been found that densities of duplex and yttria- dispersed duplex stainless steel increase from 71% to 91% and 78% to 94%, respectively, with the increase in sintering temperature. Similarly, hardness value increases from 257 to 567 HV25 in case of duplex, and from 332 to 576 HV25 in yttria-dispersed duplex stainless steel. X-ray diffraction analysis shows the domination of more intense austenite phase than ferrite at higher sintering temperature and also in nitrogen atmosphere. It is also evident that addition of yttria enhances phase transformation from a-Fe to 7-Fe. duplex and yttria-dispersed duplex stainless steels exhibit the maximum com- pressive yield strength of 360 and 312 MPa, respectively.

关键词： Nano-Y2O3 Composites Stainless steel Powder metallurgy (PM) Mechanical properties Microstructure Phase transitions

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Magnetic susceptibility measurements on metakaolin admixtured cement hydrated with ground water and sea water

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International Journal of Minerals,Metallurgy and Materials 2009年第3期16卷 349-354页

作者： d. Govindarajan r. Gopalakrishnan department of Physics Annamalai University Annamalai Nagar608002 Tamilnadu India

The role of metakaolin in the properties of Portland cement hydrated with ground water and sea water was described by magnetic susceptibility study. Cement pastes containing 0wt%, 10wt%, 20wt% and 30wt% replacement of metakaolin and in a water/cement （W/C） ratio of 0.4 were prepared. The susceptibility at different hydration periods was determined by Faraday Curie balance and it was related to the changes in setting time and compressive strength of admixtured cement. Compared with sea water-treated cement paste, the magnetic susceptibility of ground water-treated cement paste is higher in value. The observed result shows that, irrespective of water, the magnetic susceptibility increases with increasing metakaolin percentage replacement level in cement.

关键词： magnetic susceptibility admixtured cement hydration pozzolanic activity sea water

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Medium Access Control QoS Analysis in VANET, FANET Software defined radio Platform

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Engineering(科研) 2025年第1期17卷 91-106页

作者： Pegdwindé Justin Kouraogo Hamidou Harouna Omar désiré Guel department of Computer Science Joseph Ki-Zerbo University Ouagadougou Burkina Faso doctoral School of Science and Technology Aube Nouvelle University Ouagadougou Burkina Faso

Vehicular Ad Hoc Networks (VANETs) are critical for the advancement of Intelligent Transportation Systems (ITS), enabling real-time vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications. However, ensuring Quality of Service (QoS) in VANETs is challenging due to high mobility, dynamic topologies, and interference. This study evaluates the performance of Medium Access Control (MAC) protocols implemented on a Software-defined radio (Sdr) platform to address these challenges. The research highlights the use of QoS-prescribed scheduling algorithms and multi-user detection techniques to optimize key performance metrics such as packet delivery ratio (Pdr), throughput, and scalability. Simulation results demonstrate significant improvements under varying mobility and channel conditions, achieving stable communication and high user capacity in both fixed and high-mobility scenarios. The findings underscore the potential of Sdr-based VANET solutions for enhancing reliability, scalability, and efficiency in dynamic vehicular environments. Future directions include incorporating iterative methods and real-world testing to further refine QoS delivery in VANETs.

关键词： VANET Medium Access Control (MAC) Quality of Service (QoS) Software-defined radio (Sdr) Mobility Intelligent Transportation Systems (ITS)

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Medium Access Control rate Optimization in VANET, FANET Software defined radio Platform

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Engineering(科研) 2025年第1期17卷 107-123页

Vehicular Ad Hoc Networks (VANETs) play a pivotal role in the advancement of Intelligent Transportation Systems (ITS), facilitating real-time communication among vehicles (V2V) and between vehicles and infrastructure (V2I). However, maintaining reliable Quality of Service (QoS) in these dynamic environments remains challenging due to high mobility, frequent topology changes and interference. This paper proposes a robust cross-layer framework that integrates channel prediction and dynamic rate adaptation to address these challenges. The framework employs advanced multi-user detection techniques, including matched filters, successive interference cancellation (SIC), decorrelators and MMSE receivers, combined with adaptive multi-factor spreading, multi-code and multi-modulation transmission strategies. The study evaluates the framework’s performance through extensive simulations using a Software-defined radio (Sdr) platform. Key findings demonstrate significant improvements in packet reception rate, throughput and spectral efficiency under various mobility and channel conditions. The proposed approach effectively mitigates interference and adapts to dynamic network environments, showcasing its potential to enhance reliability, scalability and efficiency in VANETs. Future work will explore real-world implementation and iterative algorithmic enhancements to further optimize QoS delivery in highly variable vehicular communication scenarios.

关键词： VANET Medium Access Control (MAC) Cross-Layer design Quality of Service (QoS) Software-defined radio (Sdr) Intelligent Transportation Systems (ITS)

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Channel Prediction for MAC Optimization in VANET, FANET Software defined radio Platform

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Engineering(科研) 2025年第1期17卷 124-135页

This work addresses the critical challenge of ensuring reliable communication in vehicular ad hoc networks (VANETs) and drone networks (FANETs) under dynamic and high-mobility conditions. Current methods often fail to adequately predict rapid channel variations, leading to increased packet loss and degraded Quality of Service (QoS). To bridge this gap, we propose a novel cross-layer framework that integrates physical channel prediction into the Medium Access Control (MAC) layer to optimize network performance. Our framework employs an ArIMA (1, 0, 1) model for real-time channel prediction and dynamically adjusts MAC layer parameters to enhance throughput and reliability. Simulations demonstrate a 25% improvement in useful throughput and a 30% reduction in packet loss rates compared to baseline methods. These improvements enable practical applications in intelligent transportation systems and the efficient management of autonomous drones. Key contributions include: 1) development of a cross-layer framework that integrates channel prediction and MAC optimization. 2) demonstration of the framework’s effectiveness through Monte Carlo simulations in high-mobility scenarios. 3) Quantitative validation of enhanced throughput and reliability, highlighting the system’s potential for real-world deployment.

关键词： Prediction Cross-Layer Multiuser detection Packet Error rate Goodput

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dynamic Evolution of the Joal and djiffère Spits under the Influence of Atlantic Ocean Activity

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Journal of Environmental Protection 2025年第1期16卷 20-34页

作者： Madièye Fall déthié Sarr Oustasse A. Sall dpartment de Gotechnique L2M UFR Sciences de LIngnieur Universit Iba Der Thiam de This This Sngal dpartment de Gnie Civil UFR Sciences de LIngnieur Universit Iba Der Thiam de This This Sngal

Changes in the coastline are characterized by accretion and erosion. The aim of this study is to contribute to a better understanding of the dynamics of the coastline and the study areas with a view to mitigating and preventing the risk of coastal erosion in order to propose a coastal occupation model with planned development policies in the future. These phenomena lead to changes in the position of the coastline. After extraction, the satellite images are compiled, then superimposed and processed using Geographic Information Systems (GIS) for statistical calculation of coastline change rates. A morphosedimentary study is carried out using topography and sedimentology. The topographic method is used to calculate sediment volumes using monthly profiles. The sedimentological method is used to determine the granulometric variations in the morphological units by calculating sedimentological indices. With erosion rates of −2.13 m/yr and −2.17 m/yr respectively at djiffère (Palmarin and Sangomar breccia) and Joal (Joal Fadhiouth and Ngazobil), the EPr index revealed a sediment deficit. Palmarin Ngallou and the island of Fadhiouth are undergoing accretion at rates of +1.43 m/yr and +1.14 m/yr respectively. From a topographical point of view, the respective accumulations of −13.74 m3/m of beach and −8.65 m3/m of beach at djiffère and Joal respectively point to significant erosion on all the aerial beach units, while for the underwater beaches, accretion was noted with accumulations of +4.00 m3/m of beach and +5.94 m3/m at djiffère and Joal respectively. As for the sedimentological results, the Mz index shows a decrease in grain size from the high beach to the surf zone. Some points show bimodal deposits, showing the impact of the dune on beach activity, confirmed by the dispersion on the Mz-sigma diagram. The three methods used in this work show that the djiffère sector in Joal is dominated by erosion, even though accretion points can be noted.

关键词： Coastline Mapping Erosion Accretion Morphosedimentary

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