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Friction and wear behavior of Cu-4 wt.％Ni-TiC composites under dry sliding conditions

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Friction 2017年第4期5卷 437-446页

作者： Pushkar JHA Rakesh Kumar GAUTAM Rajnesh tyagi Department of Mechanical Engineering Indian Institute of Technology(Banaras Hindu University)Varanasi 221005India

The present study synthesized Cu-4 wt％ Ni matrix composites reinforced with different percentages of TiC (0,2,4,6,and 8 wt％) through high-energy ball milling,followed by compaction and *** friction and wear behavior was examined at four different normal loads of 5,10,15,and 20 N.A constant sliding speed of 1.25 m/s was maintained while sliding against a hardened counterface made of EN31 steel (HRC 60) under ambient conditions using a pin-on-disk test *** composite hardness increased until the addition of 4 wt％ of TiC,beyond which it was observed to *** a trend may be attributed to the TiC agglomeration in the composites containing relatively larger amounts of TiC (i.e.,6 and 8 wt％).The wear rate linearly increased with the ***,the composites exhibited a lower rate of wear than the matrix alloy,which may have resulted from the relatively higher hardness of *** observed friction and wear behavior has been explained on the basis of hardness and presence of the transfer layer on the worn surface and its nature,i.e.,loose or well *** of 4 wt％ TiC showed the optimum performance in terms of friction and wear caused by its higher hardness and ability to hold a transfer layer of a relatively larger thickness compared to the other *** wear mechanism for the Cu4Ni matrix alloy was a mix of adhesive and oxidative wear and primarily abrasive for the composites containing hard TiC particles.

关键词： sliding wear composites TiC particles friction

Three simultaneous innovations interrelationships:An adopter dynamics model

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International Journal of Modeling, Simulation, and Scientific Computing 2015年第3期6卷 116-130页

作者： Joydip Dhar Mani tyagi Poonam Sinha Department of Applied Sciences ABV-Indian Institute of Information Technology and Management Gwalior(M.P.)-474010 INDIA School of Mathematics and Allied Sciences Jiwaji University Gwalior Gwalior(M.P.)-474011INDIA

In this paper, we develop a conceptual framework of a innovation diffusion dynamicsmodel in which multiple parallel innovations are effecting each other during the diffusionprocess. A mathematical model is proposed to explore the interaction and diffusion ofthree innovations simultaneously available in market. The stability analysis is carriedout for various types of diffusions on such system both analytically and *** is observed that the association between innovations in product market could becomplementary, substitute, independent or competitive. The co-existence and extinctionof innovation depends on the level of diffusion between the innovations and it may ormay not be sensitive to initial distribution of innovations.

关键词： Adopter dynamics model association between innovations steady states dynamical behavior

Geochemistry of core sediments from the southeastern Bay of Bengal:Inferences on weathering and early diagenetic changes

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Geoscience Frontiers 2021年第2期12卷 495-504页

作者： A.Prajith Abhishek tyagi P.John Kurian National Centre for Polar and Ocean Research(NCPOR) Ministry of Earth Sciences(MoES)Headland SadaVasco-da-Gama403804GoaIndia

A sediment core(ABP24/05),collected at a water depth of 3520 m from the southeastern Bay of Bengal was studied to determine the change in chemical weathering during the last glacial to deglacial periods and the factors of sedimentary environment which controlled earliest diagenetic changes in the sediment after its *** ratios of K/Rb,Ti/Al and Zr/Rb during~45 to~18 cal kyr *** the core sediments may be attributed to the stronger physical erosion and turbidity currents activity during this *** might have brought a higher quantity of unaltered minerals to the study *** ratios of K/Rb,Zr/Rb,and Ti/Al and increase of SiO_(2)/TiO_(2),Rb/Al and Cs/Al from~18 cal kyr *** present may be indicating an increase in the rate of chemical weathering during this *** time of increased chemical weathering in the study area is consistent with deglaciation warming in the tropical Indian Ocean and strengthening of river runoff into the Andaman *** change during the interglacial period by increased solar insolation thereby strengthened the summer monsoon which might have led to intensified chemical weathering in the source region since~18 cal kyr *** low organic carbon(OC),high Mn/Al,Fe/Al and the Mn-oxides minerals precipitation indicate prevailing of oxic conditions during~11 cal kyr *** the core sediments,which is contradictory to suboxic conditions developed in the deep ocean sediments in the western Bay of Bengal and the equatorial Indian *** low terrigenous influx and export of less OC to the bottom sediments might have created a favorable condition for the formation of Mn-oxides in the study area during Holocene.

关键词： Bay of Bengal Trace elements Chemical weathering Summer monsoon Mn-oxides

Optimal Control of Nonlinear Inverted Pendulum System Using PID Controller and LQR: Performance Analysis Without and With Disturbance Input

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International Journal of Automation and computing 2014年第6期11卷 661-670页

作者： Lal Bahadur Prasad Barjeev tyagi Hari Om Gupta Department of Electrical Engineering Indian Institute of Technology Roorkee Uttarakhand 247667 India

Linear quadratic regulator(LQR) and proportional-integral-derivative(PID) control methods, which are generally used for control of linear dynamical systems, are used in this paper to control the nonlinear dynamical system. LQR is one of the optimal control techniques, which takes into account the states of the dynamical system and control input to make the optimal control *** nonlinear system states are fed to LQR which is designed using a linear state-space model. This is simple as well as robust. The inverted pendulum, a highly nonlinear unstable system, is used as a benchmark for implementing the control methods. Here the control objective is to control the system such that the cart reaches a desired position and the inverted pendulum stabilizes in the upright position. In this paper, the modeling and simulation for optimal control design of nonlinear inverted pendulum-cart dynamic system using PID controller and LQR have been presented for both cases of without and with disturbance input. The Matlab-Simulink models have been developed for simulation and performance analysis of the control schemes. The simulation results justify the comparative advantage of LQR control method.

关键词： Inverted pendulum nonlinear system proportional-integral-derivative (PID) control optimal control linear quadratic regulator (LQR)

Critical review of EPS production, synthesis and composition for sludge flocculation

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Journal of Environmental Sciences 2018年第4期30卷 225-245页

作者： Klai Nouha Ram Saurabh Kumar Sellamuthu Balasubramanian Rajeshwar Dayal tyagi Universite du Quebec Institut national de la Recherche Scientifique Centre Eau Terre & Environnement 490 de la CouronneQuebec G1K 9A9 Canada Institut Armand-Frappier 531 boul. des Prairies Laval Quebec H7V 1B7 Canada

Extracellular polymeric substances（EPS） produced by microorganisms represent biological macromolecules with unfathomable potentials and they are required to be explored further for their potential application as a bioflocculant in various wastewater sludge treatment. Although several studies already exist on biosynthetic pathways of different classical biopolymers like alginate and xanthan, no dedicated studies are available for EPS in sludge. This review highlights the EPS composition, functionality, and biodegradability for its potential use as a carbon source for production of other metabolites. Furthermore, the effect of various extraction methods（physical and chemical） on compositional, structural, physical and functional properties of microbial EPS has been addressed. The vital knowledge of the effect of extraction method on various important attributes of EPS can help to choose the suitable extraction method depending upon the intended use of EPS. The possible use of different molecular biological techniques for enhanced production of desired EPS was summarized.

关键词： Extracellular polymeric substances Metabolic pathways Extraction methods Flocculation properties

Pathology of atherosclerotic coronary artery disease in the young Indian population

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Forensic Sciences Research 2019年第3期4卷 241-246页

作者： Pradeep Vaideeswar Shashank tyagi Saranya Singaravel Department of Pathology(Cardiovascular&Thoracic Division) Seth GS Medical College&KEM HospitalMumbaiIndia Department of Forensic Medicine&Toxicology Seth GS Medical College&KEM HospitalMumbaiIndia

Atherosclerotic coronary artery disease (CAD) is of great concern in young adults because of its potential to cause great *** arena of cardiology has gained importance in South Asian countries,particularly India due to increased prevalence that is related to traditional risk factors,altered life styles and inherent risk *** this study,we sought to evaluate,at autopsy,the pathology of atherosclerotic CAD in young patients with ischemic heart disease (IHD).A 10-year retrospective autopsy-based study was carried out in a large tertiary-care centre and patients aged ≤45 years with IHD were *** of 545 autopsied cases of IHD,95 patients (17.4%) were *** these 95 patients,84 (88.4%) had IHD related to atherosclerotic CAD;the youngest patient was 18years *** there was sole involvement of left anterior descending artery and the presence of fibrous *** of the plaque morphology,the commonest complication was thrombosis produced by plaque erosion seen in 36.9% of *** coronary insufficiency was noted in 52 patients (61.9%),while healed infarctions were surprisingly noted in 28 patients (33.3%).Screening for IHD in the young population may help to improve prognosis by detecting subclinical disease,although more studies are necessary to establish reference limits for this young *** research must also focus on treatment concerns that are specific to young patients.

关键词： Forensic sciences forensic pathology ischemic heart disease coronary atherosclerosis young adults sudden cardiac death

A detailed study on trust management techniques for security and privacy in IoT:challenges,trends,and research directions

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高置信计算(英文) 2023年第2期3卷 71-82页

作者： Himani tyagi Rajendra Kumar Santosh Kr Pandey Department of Computer Science Jamia Millia IslamiaNew Delhi 110025India Department of EC&IT MeityNew Delhi 110003India

The Internet of Things is a modern technology that is directed at easing human life by automating most of the things used in daily *** never-ending dependency on the network for communication is attracting adversaries to exploit the vulnerabilities of ***,this technology is facing some serious issues and challenges concerning security and *** issues and challenges are the real motivation behind considering this ***,this survey includes a discussion about security and privacy challenges as well as available solutions for IoT based wireless sensor *** systematic literature review(SLR)focuses particularly on a popular and applicable security approach known as Trust Management System(TMS).Firstly,all aspects of trust management,including trust indicators,trust properties,trust evaluation,trust building,trust models and the importance of those models for security and privacy,trust prediction methodologies,and ultimately trust-based attacks,are covered in this ***,trust management schemes are classified into four groups based on the methodology used for trust-based security solutions in the IoT:cryptography-based,computational and probabilistic-based,information theory-based,and ***,an understanding of the problems and difficulties with current methodologies is given,along with suggestions for further ***,the SLR is concluded by formulating the desirable characteristics of a trust management system in the IoT and proposing a trust model suitable for IoT networks.

关键词： Trust Trust management approaches IoT Security Privacy Reliability Attacks Trust attributes Systematic literature review Cybersecurity

Antioxidant Machinery Related to Decreased MDA Generation by Thymus Algeriensis Essential Oil-induced Liver and Kidney Regeneration

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Biomedical and Environmental Sciences 2016年第9期29卷 639-649页

作者： Guesmi Fatma Amit K tyagi Bellamine Houda Landoulsi Ahmed Laboratory of Biochemistry and Molecular Biology Faculty of Sciences of Bizerte University of Carthage 1054 Tunisia Department of Experimental Therapeutics The University of Texas M. D. Anderson Cancer Center 1515 Holcombe Boulevard Houston TX 77030 USA Service of Anatomo-Pathology of Menzel Bourguiba Bizerte 1054 Tunisia

Objective This study was conducted to determine the histopathological and biochemical effects of Thymus algeriensis essential oil （TEO） on hydrogen peroxide （H2O2）-induced oxidative stress in liver and kidney tissues of rats. Methods Rats were treated in six groups and were exposed for 2 weeks to low （LD; 100 μmol/L） and high doses （HD; 1 mmol/L） of H2O2 in the presence or absence of TEO （180 mg/kg）. Liver and kidney atrophy was measured by using biochemical and histopathological assays. Results Our study demonstrated that H2O2 induced liver and kidney atrophy, as evidenced by the significant elevation of serum aminotransferase, urea, and creatinine levels compared with those in the control rats. Urea levels were estimated by evaluating the activity of serum urease that hydrolyzes urea into CO2 and ammonia. However, TEO treatment significantly alleviated oxidative stress in the H2O2-induced liver and kidney toxicity model by reducing the levels of malondialdehyde concomitantly with marked elevations in superoxide dismutase, catalase, glutathione peroxidase, and glutathione S-transferase, as well as decrease in glutathione activity. Conclusion Our data demonstrated that TEO protected against H202 toxicity by decreasing oxidant levels and DNA damage, as well as increasing antioxidant levels, indicating that TEO has a spectrum of antioxidant and DNA-protective properties.

关键词： Liver and kidney atrophy Hydrogen peroxide Thymus algeriensis Antioxidants Toxicity

Experimental study of laser cladding process and prediction of process parameters by artificial neural network(ANN)

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Journal of Central South University 2022年第10期29卷 3489-3502页

作者： Rashi tyagi Shakti KUMAR Mohammad Shahid RAZA Ashutosh TRIPATHI Alok Kumar DAS University Centre for Research and Development Chandigarh UniversityMohali-140413India Department of Mechanical Engineering Chandigarh UniversityMohali-140413India Department of Mechanical Engineering IIT(ISM)Dhanbad-826004India Department of Mechanical Engineering IIT KharagpurIndia

Laser cladding of powder mixture of TiN and SS304 is carried out on an SS304 substrate with the help of fibre *** experiments are performed on SS304,as per the Taguchi orthogonal array(L^(16))by different combinations of controllable parameters(microhardness and clad thickness).The microhardness and clad thickness are recorded at all the experimental runs and studied using Taguchi S/N ratio and the optimum controllable parametric combination is ***,an artificial neural network(ANN)identifies different sets of optimal combinations from Taguchi method but they both got almost the same clad thickness and hardness *** micro-hardness of cladded layer is found to be6.22 times(HV_(0.5)752)the SS304 hardness(HV_(0.5)121).The presence of nitride ceramics results in a higher micro *** cladded surface is free from cracks and *** average clad thickness is found to be around 0.6 mm.

关键词： laser cladding Taguchi orthogonal array artificial neural network microhardness microstructure