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Tribological and wear performance of centrifuge cast functional graded copper based composite at dry sliding conditions

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Journal of Central South University 2019年第11期26卷 2961-2973页

作者： n.radhika Manu SAM Deptartment of Mechanical Engineering Amrita School of Engineering

non lubricated slide performance of functional grade copper matrix composite,fabricated using horizontal centrifuge cast technique was investigated using pin-on-disc *** of wear and friction coefficient of the inner wall thickness of hollow cylindrical cast specimen was analyzed using Taguchi based L27 orthogonal array,where the percentage of graphite particles were observed *** process parameters those influenced the rate of wear directly or indirectly were:applied load(15,25 and 35 n),slide velocity(1.5,2.5 and 3.5 m/s)and slide distance(750,1500 and 2250 m).Rate of wear and friction coefficient showed a proportional dependency with applied load and slide distance,whereas showing a decline during intermediate slide ***-to-noise ratio predicted the minimal tribo-condition,on‘smaller-the-better’*** of Variance technique quantified the influence of affecting parameters,along with their *** analysis was utilized for the validation of the experimental *** and scanning electron microscopy exhibited the wear mechanisms and mechanically mixed layer formation during worn surfaces analysis.

关键词： functional graded materials centrifuge casting adhesive wear Taguchi tribology

Development of functionally graded aluminium composites using centrifugal casting and influence of reinforcements on mechanical and wear properties

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Transactions of nonferrous Metals Society of China 2016年第4期26卷 905-916页

作者： n.radhika R.RAGHU Department of Mechanical Engineering Amrita Vishwa VidyapeethamCoimbatore-641 112India

Functionally graded Al/B_4C, Al/Si C, Al/Al_2O_3 and Al/TiB_2 composites with constant 12%(mass fraction) of reinforcement were fabricated by centrifugal casting and hollow cylindrical components were obtained. Microstructural characteristics were investigated at outer surface of all composites and segregation of reinforcement particles was observed. Graded property of the composites with different reinforcements was investigated through hardness and tensile measurements. Results revealed that the outer peripheries of all composites exhibit higher hardness except in Al/B_4C composite and the outer zones of all composites show higher tensile strength. Abrasive wear test was conducted on the outer peripheries of all composites and Al/TiB_2 composite exhibits less wear rate.

关键词： functionally graded composite centrifugal casting mechanical properties abrasive wear

Effect of reinforcement content on the adhesive wear behavior of Cu10Sn5ni/Si3n4 composites produced by stir casting

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International Journal of Minerals,Metallurgy and Materials 2017年第9期24卷 1052-1060页

作者： K.Sanesh S.Shiam Sunder n.radhika Department of Mechanical Engineering Amrita School of EngineeringCoimbatore 64112Amrita Vishwa VidyapeethamAmrita UniversityIndia

The main objective of this paper was to fabricate CuSnni alloy and its composites reinforced with various contents of Sinparticles(5wt%, 10wt%, and 15wt%) and to investigate their dry sliding wear behavior using a pin-on-disk tribometer. Microstructural examinations of the specimens revealed a uniform dispersion of Sinparticles in the copper matrix. Wear experiments were performed for all combinations of parameters, such as load(10, 20, and 30 n), sliding distance(500, 1000, and 1500 m), and sliding velocity(1, 2, and 3 m/s), for the alloy and the composites. The results revealed that wear rate increased with increasing load and increasing sliding distance, whereas the wear rate decreased and then increased with increasing sliding velocity. The primary wear mechanism encountered at low loads was mild adhesive wear, whereas that at high loads was severe delamination wear. An oxide layer was formed at low velocities, whereas a combination of shear and plastic deformation occurred at high velocities. The mechanism at short sliding distances was ploughing action of Sinparticles, which act as protrusions; by contrast, at long sliding distances, direct metal–metal contact occurred. Among the investigated samples, the Cu/10wt% Sincomposite exhibited the best wear resistance at a load of 10 n, a velocity of 2 m/s, and a sliding distance of 500 m.

关键词： copper matrix composites stir casting adhesive wear wear mechanisms

Automatic area estimation of algal blooms in water bodies from UAV images using texture analysis

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Water Science and Engineering 2024年第1期17卷 62-71页

作者： Ajmeria Rahul Gundu Lokesh Siddhartha Goswami R.n.Ponnalagu radhika Sudha Department of Electrical and Electronics Engineering Birla Institute of Technology&SciencePilani Hyderabad CampusTelangana 500078India

Algal blooms,the spread of algae on the surface of water bodies,have adverse effects not only on aquatic ecosystems but also on human *** adverse effects of harmful algal blooms(HABs)necessitate a convenient solution for detection and *** aerial vehicles(UAVs)have recently emerged as a tool for algal bloom detection,efficiently providing on-demand images at high spatiotemporal *** study developed an image processing method for algal bloom area estimation from the aerial images(obtained from the internet)captured using *** a remote sensing method of HAB detection,analysis,and monitoring,a combination of histogram and texture analyses was used to efficiently estimate the area of *** features like entropy(using the Kullback-Leibler method)were emphasized with the aid of a gray-level co-occurrence *** results showed that the orthogonal images demonstrated fewer errors,and the morphological filter best detected algal blooms in real time,with a precision of 80%.This study provided efficient image processing approaches using on-board UAVs for HAB monitoring.

关键词： Algal bloom Image processing Texture analysis Histogram analysis Unmanned aerial vehicles

User Perspective of Misplaced PPIUCD and Factors Resulting in PPIUCD Removal: Qualitative Pilot Study

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Open Journal of Epidemiology 2024年第3期14卷 517-532页

作者： A. G. radhika Rashmi Gupta Pooja Kashyap Ravleen Bakshi Department of Obstetrics and Gynecology University College of Medical Sciences & Guru Teg Bahadur Hospital Dilshad Garden Delhi India GTB Hospital Delhi India Indian Council of Medical Research Delhi India

Objective: The aim of the current study was to assess the impact of operative interventions for misplaced device among women who opted for PPIIUCD and the evaluation of reasons for PPIUCD removal within the follow up period of two years. Design: A descriptive exploratory study was conducted over three months among fourteen PPIUCD acceptors at a tertiary care health facility in Delhi, India. Face-to-face & telephonic in-depth interviews were conducted with a selected sample of PPIUCD acceptors who had later opted for its removal. Results: Participants (n = 14) aged 24 – 40 exhibited generally positive attitudes towards PPIUCDs indicating an indicate an understanding of the importance of PPIUCD in preventing unintended pregnancies. Menstrual disturbance and misplaced IUCD were major reasons for removal. despite their own experience necessitating the removal of IUCD, positive experience by other family members (mothers in law) in this study helped to keep the confidence on the contraceptive. Themes included (a) general experience of PPIUCD use (b) Health Facility accessed for removal of IUCD (c) Would she recommend it to others? (d) preferred contraceptive after removal of IUCD. Conclusion: Misplaced IUCD, missing thread, menstrual irregularities, and pain are all associated with PPIUCD and are important reasons for dissatisfaction. Appropriate, timely and supportive individualized care that address knowledge gaps, societal perceptions, and healthcare system challenges would certainly help in reducing dissatisfaction due to PPIUCD and thereby the removal rates.

关键词： Postpartum Intrauterine Device PPIUCD LARC Long Acting Reversible Contraception Postpartum Family Planning Contraception

CLAY CATALYZED SYnTHESIS OF BIO-DEGRADABLE POLY(GLYCOLIC ACID)

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Chinese Journal of Polymer Science 2008年第4期26卷 393-398页

作者： K.Durai Murugan S.radhika I.Baskaran R.Anbarasan Department of Chemistry S.N.CollegeMadurai-625022Tamil NaduIndia Advanced nanotechnology Research Laboratory Department of Polymer TechnologyKamaraj College of Engineering and TechnologyVirudhunagar-626001Tamil NaduIndia

Glycolic acid was polymerized under vacuum in the presence and absence of nano sized *** added clay catalyzed the condensation polymerization which can be confirmed by recording FTIR spectroscopy and intrinsic viscosity (Ⅳ)*** relative intensity of C=O/CH is increased while increasing the amount of *** showed the appearance of multiple endotherms of poly(glycolic acid).TGA showed the percentage weight residue remain above 750℃for polymer-nano composite system was 21% and hence proved the fl...

关键词： Synthesis Poly(glycolic acid) Clay FTIR DSC TGA Intrinsic viscosity

Tribological Behaviour of Aluminium/Alumina/Graphite Hybrid Metal Matrix Composite Using Taguchi’s Techniques

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Journal of Minerals and Materials Characterization and Engineering 2011年第5期10卷 427-443页

作者： n. radhika R. Subramanian S. Venkat Prasat Amrita School of Engineering Amrita Vishwa Vidyapeetham Coimbatore-641 105. PSG College of Technology Coimbatore-641 004.

Tribological behaviour of aluminium alloy (Al-Si10Mg) reinforced with alumina (9%) and graphite (3%) fabricated by stir casting process was investigated. The wear and frictional properties of the hybrid metal matrix composites was studied by performing dry sliding wear test using a pin-on-disc wear tester. Experiments were conducted based on the plan of experiments generated through Taguchi’s technique. A L27 Orthogonal array was selected for analysis of the data. Investigation to find the influence of applied load, sliding speed and sliding distance on wear rate, as well as the coefficient of friction during wearing process was carried out using AnOVA and regression equations for each response were developed. Objective of the model was chosen as ‘smaller the better’ characteristics to analyse the dry sliding wear resistance. Results show that sliding distance has the highest influence followed by load and sliding speed. Finally, confirmation tests were carried out to verify the experimental results and Scanning Electron Microscopic studies were done on the wear surfaces.

关键词： Metal Matrix Composites Stir casting Taguchi’s techniques Orthogonal array Analysis of variance wear behaviour.

Fight against COVID-19: Survey of Spices &Herbs Used in north India

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Open Journal of Epidemiology 2021年第3期11卷 256-266页

作者： Ayalur Gopalakrishnan.radhika Himani Malik Department of Obstetrics and Gynecology University College of Medical Sciences & Guru Teg Bahadur Hospital Delhi India

Treatments for the ongoing COVID-19 global pandemic continue to be researched. Clinical trials with antivirals or immunomodulators have met with variable success. Traditional herbal remedies for health problems are popular for prevention and treatment of ailments especially in low resource countries. It is notable that morbidity and mortality from COVID were lower in low resource countries compared to the west. Other factors attributed to this difference include ethnicity, temperature, humidity, innate immunity, and nutrition.ng> Objective: ng>To identify the traditional herbs used for protection against COVID, in north India. ng>Method:ng> This questionnaire-based survey was conducted from August to September 2020 at five districts in north India. Participation in the brief interview was voluntary. Responses were recorded in a predesigned questionnaire (Annexure). Descriptive data analysis was done.ng> Results:ng> A total of 250 people participated in the interview. Majority (84.4%) of the respondents used mask. A total of 66.8% of the respondents confirmed using traditional herbs and spices. Most frequently used home remedies were decoction of herbs including ginger, Tinospora cordifolia, turmeric, black pepper, carom seeds. Turmeric milk was also popular choice. COVID positivity was present in family members of 4% (n = 10) of the respondents, of these four did not consume any herbs. ng>Conclusions: ng>This study provides an overview on the use of home remedies in north India. Given the scarcity of reliable information on home remedies and traditional medicines, further research is needed to develop robust evidence for their role in disease prevention and treatment.

关键词： Home Remedies Kadha Traditional Medicine COVID Corona Spices Herbs Minor Health Ailments

Click Reaction Functionalization of Hydroxylated nanoparticles by Cyclic Azasilanes for Colloidal Stability in Oilfield Applications

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Advances in nanoparticles 2021年第1期10卷 36-49页

作者： radhika Suresh Sankaran Murugesan Valery Khabashesku Center for Technology Innovation Baker Hughes Houston TX USA Department of Materials Science and nanoengineering Rice University Houston TX USA

The growing interest in functionalized nanoparticles and their implementation in oilfield applications (e.g., drilling fluids and enhanced oil recovery (EOR)) facilitate the ongoing efforts to improve their chemical f... 详细信息

The growing interest in functionalized nanoparticles and their implementan>n>tion in oilfield applications (e.g., drilling fluids and enhanced oil recoveryn>n> (EOR)) facilitate the ongoing efforts to improve their chemical functionalization performance in stabilization of water based or hydrocarbon based nanofluids. Cyclic azasilanes (CAS), substituted 1-aza-2-silacyclopentanes, possess a strained 5-member ring structure. Adjacent Si and N atoms in the ring provide opportunity for highly efn>n>ficient covalent surface functionalization of hydroxylated nanoparticles through a catalyst-free and byproduct-free click reaction. In this work, hydroxylated silica, alumina, diamond, and carbon coated iron core-shell nanoparticles have been studied for monolayer CAS functionalization. Two cyclic azasilanes with different R groups at N atom, such as methyl (CAS-1) and aminoethyl (CAS-2), have been utilized to functionalize nanoparticles. All reactions were found to readily proceed under mild conditions (room temperature, ambient pressure) during 1 - 2 hours of sonication. CAS functionalized adducts of hydroxylated nanoparticles have been isolated andn>n>n> n>n>n>n>n style="font-family:"">their microstructure, composition, solubility and thermal stability have been characterized. As a result, it has been demonstrated, for the first time, that covalent surface modification with cyclic azasilanes can be extended beyond the previously known porous silicon structures to hydroxylated silica, alumina and carbon nanoparticles. The developed methodology was also shown to provide access to the nanoparticles with the hydrophilic or hydrophobic surface functional

关键词： Functionalization Azasilane nanoparticles Colloidal Stability Oilfield Applications