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propulsion and power Research 2015年第3期4卷 150-160页

作者： p.v.satya narayana Fluid Dynamics Division SASVIT UniversityVellore-632014T.NIndia

An analysis has been carried out to study the effects of radiation absorption and firstorder chemical reaction on unsteady mixed convective flow of a viscous incompressible electrically conducting fluid through a porous medium of variable permeability between two long vertical non conducting wavy channels in the presence of heat *** unsteadiness in the flow is due to traveling thermal wave imposed on the *** governing equations are solved subject to the relevant boundary conditions with the assumption that the solution consists of a mean part and a perturbed *** zeroth-order,the first order and the total solution of the problem are numerically evaluated and displayed graphically for pertinent *** model finds applications in studying fixed-bed catalytic reactors and packed bed heat exchangers.

关键词： Magnetohydrodynamic(MHD) Chemical reaction Traveling thermal waves Radiation absorption variable permeability

A review on the current status of Fe-Al based ferritic lightweight steel

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Defence Technology（防务技术） 2023年第8期26卷 1-22页

作者： Shivkumar Khaple Brahma Raju Golla v.v.satya prasad Defence Metallurgical Research Laboratory HyderabadIndia Metallurgical and Materials Engineering Department National Institute of TechnologyWarangalIndia

There is an ever-growing demand for lightweighting of steel for structural applications,particularly for automobile and transportation *** is mainly to improve the fuel efficiency,reduce the CO_(2) emissions and cater the increased passenger ***,the main focus is to reduce the density of the steel structure without affecting other *** can be achieved by down-gauging of the conventional steel by replacing the steel with higher strength,however,it is limited by dent resistance and ***,the novel idea is to reduce the density of the steel *** is well-known that addition of Al to steel reduces the density of the *** 1wt% of Al addition to steel can reduce the density by 1.3%,decreases the elastic modulus by 2% and it improves the strength by about 40 *** is a new class of low-density/lightweight steel with addition of about 6-9 wt% Al to *** of higher than 9 wt%of Al in steel leads to embrittlement issues due to ordering and environmental *** disordered Fe-Al lightweight steels have raised considerable interest due to their low-density,high ductility,costeffectiveness and feasibility for bulk *** low-density steels are envisaged in the development of an advanced lightweight ground transportation system,huge structures and also for certain defence applications and in thermal power plants.

关键词： Low-density steels Disordered FeeAl Thermo-mechanical processing Microstructure properties Structure-property correlation

Microstructure and texture evolution in AZ31 magnesium alloy during caliber rolling at different temperatures

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Journal of Magnesium and Alloys 2017年第3期5卷 340-347页

作者： Abhishek Tripathi S.v.S.narayana Murty p.Ramesh narayanan Department of Metallurgical Engineering and Materials Science Indian Institute of Technology BombayMumbai 400076India Materials Characterisation Division Materials and Metallurgy GroupVikram Sarabhai Space CentreTrivandrum 695022India

Magnesium alloy AZ31 was caliber rolled at different temperatures viz.523K,573K,623K,673K and 723K imposing a total cumulative reduction of 92%and a cumulative strain of *** associated microstructure and texture evolution were studied using Electron Back Scattered Diffraction(EBSD)and X-ray macro-texture observations *** refinement was observed in all the caliber rolled bars indicating the occurrence of dynamic *** parameter and texture index were used to study the evolution of *** doubling of the yield strength at room temperature was observed by caliber rolling at a temperature of *** improvement in mechanical properties was explained on the basis of the fine grain microstructures and suitable development of crystallographic *** on the present study,warm caliber rolling can be used as a good production method for obtaining long bars of high strength magnesium alloy AZ31.

关键词： Magnesium alloy AZ31 Microstructure Caliber rolling Texture

Metallurgical analysis of a failed maraging steel shear screw used in the band separation system of a satellite launch vehicle

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Defence Technology（防务技术） 2016年第5期12卷 380-387页

作者： S.v.S. narayana MURTY Sushant K. MANWATKAR E Ramesh narayanaN Material Characterization Division Materials and Metallurgy Group Vikram Sarabhai Space Centre Trivandrum 695 022 India

Maraging steels have excellent combination of strength and toughness and are extensively used for a variety of aerospace applications. In one such critical application, this steel was used to fabricate shear screws of a stage separation system in a satellite launch vehicle. During assembly preparations, one of the shear screws which connected the separation band and band end block has failed at the first thread. Microstructural analysis revealed that the crack originated from the root of the thread and propagated in an intergranular mode. The failure is attributed to combined effect of stress and corrosion leading to stress corrosion cracking.

关键词： M250 grade maraging steel Shear screw Separation system Mermen band Stress corrosion cracking

Microstructure, properties and hot workability of M300 grade maraging steel

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Defence Technology（防务技术） 2018年第1期14卷 51-58页

作者： K.v.A.Chakravarthi N.T.B.N.Koundinya S.v.S.narayana Murty B.Nageswara Rao Materials and Mechanical Entity Vikram Sarabhai Space Centre Research scholar Department of Mechanical Engineering K L University Department of Metallurgical Engineering and Materials Science Indian Institute of Technology Department of Mechanical Engineering K L University

This paper presents isothermal uniaxial compression test results of M300 grade maraging steel over a wide range of temperatures(900 e1200℃) and strain rates(0.001 e100 s^(-1)) to examine hot deformability and concurrent microstructural evolution. processing map is generated and indicated the optimum processing parameters in the temperature range of 1125℃-1200℃ and strain rate range of 0.001 e0.1 s^(-1). High values of the efficiency of power dissipation, microstructural observations and EBSD results indicate softening mechanism to be the occurrence of dynamic recrystallisation. Material constants in a constitutive relation are evaluated from the flow stress data useful in computer modelling.

关键词： Activation energy Constitutive relation Hot deformation M300 grade maraging steel processing map

The role and significance of Magnesium in modern day research-A review

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Journal of Magnesium and Alloys 2022年第1期10卷 1-65页

作者： S v satya prasad S B prasad Kartikey verma Raghvendra Kumar Mishra vikas Kumar Subhash Singh Department of production and Industrial Engineering National Institute of Technology JamshedpurJharkhand831014India Department of Chemical Engineering Indian Institute of TechnologyKanpur208016India Enhanced Composites and Structures Center School of AerospaceTransport and ManufacturingCranfield UniversityBedfordshire MK43 OALUK Department of Automotive Technology Mechanical Department DivisionFederal TVET instituteAddis AbabaEthiopia

Magnesium is one of the largely available elements in the earth’s crust. It has a low structural density with high specific strength. This unique material property has forced an increase in the use of magnesium and its alloys in various applications pertaining to industrial sector,automobiles, aerospace and biomedical. Since magnesium is a highly reactive metal, it is prone to higher rate of corrosion as compared to its counterparts. Thus, it is essential to analyze the corrosion behavior of magnesium and its alloys in its applications. An appropriate process is to be followed in the design and development of magnesium alloys which overcome the limitations of magnesium and enhance the desired material properties in accordance to their applications. This review paper summarizes the importance of magnesium and its material properties. The influence of various alloying elements on the mechanical properties of magnesium is reviewed. The broad classification of Mg alloys and their behavioral trends are detailed. The corrosion behavior of magnesium and the influence of corrosion products on the material characteristics of magnesium, in aqueous medium, are discussed. The manufacturing techniques of magnesium alloys along with the secondary techniques are also covered. The various applications and the limitations of magnesium in these applications are covered. A complete section is dedicated towards detailing the recent trends of magnesium(Mg) alloys, i.e., the biodegradable nature and applications of Mg alloys. The influence of biocorrosion on Mg alloys and techniques to overcome it have been deliberated. This paper provides a thorough review on recent developments of magnesium with respect to engineering applications.

关键词： Magnesium alloys Biodegradable alloys Magnesium corrosion Biocorrosion

High Efficiency SiC Terahertz Source in Mixed Tunnelling Avalanche Transit Time Mode

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World Journal of Nano Science and Engineering 2014年第4期4卷 143-150页

作者： pranati panda satya narayana padhi Gana Nath Dash Electron Devices Group School of Physics Sambalpur University Burla India

High frequency properties of 4H-SiC double drift region (DDR) Mixed Tunnelling Avalanche Transit Time (MITATT) diodes are studied through computer simulation method. It is interesting to observe that the efficiency of SiC (flat) DDR MITATT diode (16%) is more than 4 times that of Si (flat) DDR MITATT diode (3.59%). In addition, a power output of more than 15 times from the SiC MITATT diode compared to the Si MITATT diode is commendable. A reduced noise measure of 17.71 dB from a low-high-low (lo-hi-lo) structure compared to that of 21.5 dB from a flat structure of SiC is indicative of the favourable effect of tunnelling current on the MITATT diode performance.

关键词： MITATT SiC Terahertz Tunnelling

A novel protocol for reviving of oil and natural gas wells

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petroleum Research 2019年第3期4卷 276-281页

作者： R.v.v.Ramana Murthy Naresh Kumar Katari N.satya Sree Sreekantha B.Jonnalagadda Division of Chemistry Vignan's Foundation for ScienceTechnology and Research UniversityVadlamudiGuntur 522213 Andhra PradeshIndia Department of Chemistry GITAM deemed to be UniversityHyderabad502329TelanganaIndia School of Chemistry&physics Westville CampusUniversity of KwaZulu-NatalP Bag X 54001Durban 4000South Africa

For effective cleaning of oil and gas wells and their revival,a novel fluid composition of enzyme-G with acid mixture together with corrosion inhibitor and selected additives is *** and field experiments endorse the effectiveness of the new fluid *** testing and analyzing the results with various treatment combinations,the procedure is *** efficacy is validated by treating various oil and natural gas *** communication provides a comprehensive description of the method for cleaning the oil and gas wells and their stimulation for improving the *** novel enzymes-G composition developed,effectively removes the impurities from the face of the wellbore,improve pore formation and create additional artificial channels to enhance the production of oil and *** developed protocols could also be used in injection wells to improve the injection rates.

关键词： Well stimulation polymers breaking Acidization Fragmentation Corrosion inhibitor Enzyme G

Breath tests and irritable bowel syndrome

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World Journal of Gastroenterology 2014年第24期20卷 7587-7601页

作者： satya vati Rana Aastha Malik Department of Super Specialty Gastroenterology Post Graduate Institute of Medical Education and ResearchSector 12Chandigarh 160012India

Breath tests are non-invasive tests and can detect H2 and CH4 gases which are produced by bacterial fermentation of unabsorbed intestinal carbohydrate and are excreted in the breath. These tests are used in the diagnosis of carbohydrate malabsorption, small intestinal bacterial overgrowth, and for measuring the orocecal transit time. Malabsorption of carbohydrates is a key trigger of irritable bowel syndrome (IBS)-type symptoms such as diarrhea and/or constipation, bloating, excess flatulence, headaches and lack of energy. Abdominal bloating is a common nonspecific symptom which can negatively impact quality of life. It may reflect dietary imbalance, such as excess fiber intake, or may be a manifestation of IBS. However, bloating may also represent small intestinal bacterial overgrowth. patients with persistent symptoms of abdominal bloating and distension despite dietary interventions should be referred for H2 breath testing to determine the presence or absence of bacterial overgrowth. If bacterial overgrowth is identified, patients are typically treated with antibiotics. Evaluation of IBS generally includes testing of other disorders that cause similar symptoms. Carbohydrate malabsorption (lactose, fructose, sorbitol) can cause abdominal fullness, bloating, nausea, abdominal pain, flatulence, and diarrhea, which are similar to the symptoms of IBS. However, it is unclear if these digestive disorders contribute to or cause the symptoms of IBS. Research studies show that a proper diagnosis and effective dietary intervention significantly reduces the severity and frequency of gastrointestinal symptoms in IBS. Thus, diagnosis of malabsorption of these carbohydrates in IBS using a breath test is very important to guide the clinician in the proper treatment of IBS patients.

关键词： Bacterial overgrowth Breath test Carbohydrate malabsorption Irritable bowel syndrome Lactulose breath test Small intestine Sorbitol breath test

Enhanced Energy Efficient with a Trust Aware in MANET for Real-Time Applications

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Computers, Materials & Continua 2023年第4期75卷 587-607页

作者： M.v.narayana vadla pradeep Kumar Ashok Kumar Nanda Hanumantha Rao Jalla Subba Reddy Chavva Department of CSE Guru Nanak Institutions Technical CampusHyderabadRanga Reddy DistrictTelangana501506India Department of CSE B V Raju Institute of TechnologyNarsapurMedakTelangana502313India Department of CSE T.R.R.Government Degree College KandukurKandukurA.P.523105India Department of IT VFST&Research(Deemed to be University)VadlamudiA.P.522213India

Mobile ad hoc networks (MANETs) are subjected to attack detectionfor transmitting and creating new messages or existing message *** attacker on another node evaluates the forging activity in themessage directly or indirectly. Every node sends short packets in a MANETenvironment with its identifier, location on the map, and time through *** attackers on the network broadcast the warning message usingfaked coordinates, providing the appearance of a network collision. Similarly,MANET degrades the channel utilization performance. performancehighly affects network performance through security algorithms. This paperdeveloped a trust management technique called Enhanced Beacon TrustManagement with Hybrid Optimization (EBTM-Hyopt) for efficient clusterhead selection and malicious node detection. It tries to build trust amongconnected nodes and may improve security by requiring every participatingnode to develop and distribute genuine, accurate, and trustworthy materialacross the network. Specifically, optimized cluster head election is done periodicallyto reduce and balance the energy consumption to improve the lifetimenetwork. The cluster head election optimization is based on hybridizingparticle Swarm Optimization (pSO) and Gravitational Search OptimizationAlgorithm (GSOA) concepts to enable and ensure reliable routing. Simulationresults show that the proposed EBTM-HYOpT outperforms the state-of-thearttrust model in terms of 297.99 kbps of throughput, 46.34% of pDR, 13%of energy consumption, 165.6 kbps of packet loss, 67.49% of end-to-end delay,and 16.34% of packet length.

关键词： MANET malicious nodes clustering trust management beacon message