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Acta metallurgica Sinica(English Letters) 2015年第2期28卷 208-215页

作者： m.manikandan N.Arivazhagan m.nageswara rao G.madhusudhan Reddy School of mechanical and Building Sciences VIT University Defence metallurgical and Research Laboratory

Superalloy C-276 is known to be prone to hot cracking during fusion welding by Gas Tungsten Arc method. microsegregation occurring during cooling of fusion zone with consequent appearance of topologically close-packed phases P and IX has been held responsible for the observed hot cracking. The present work investigated the possibility of suppressing the microsegregation in weldments by resorting to current pulse. Weldments were made by continuous current gas tungsten arc welding and pulsed current gas tungsten arc welding using ERNiCrmo-4 filler wire. The weld joints were studied with respect to microstructure, microsegregation, and mechanical properties. Optical microscopy and scanning electron microscopy were employed to study the microstructure. Energy-Dispersive X-ray Spectroscopy was carried out to evaluate the extent of microsegregation. Tensile testing was carried out to determine the strength and ductility. The results show that the joints fabricated with pulsed current gave rise to narrower welds with practically no heat affected zone, a refined microstructure in the fusion zone, reduced microsegregation, and superior combination of mechanical properties.

关键词： Alloy C-276 Pulsed current gas tungsten arc welding microsegregation

Effect of pulsed current micro plasma arc welding process parameters on fusion zone grain size and ultimate tensile strength of Inconel 625 sheets

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Acta metallurgica Sinica(English Letters) 2012年第3期25卷 179-189页

作者： Kondapalli Siva Prasad Chalamalasetti Srinivasa rao Damera nageswara rao Department of mechanical Engineering Anil Neerukonda Institute of Technology & SciencesVisakha- patnam India Department of mechanical Engineering AU College of Engineering Andhra UniversityVisakhapat- nam India Centurion University of Technology & management Odisha India

The paper focuses on developing mathematical models to predict grain size and ul- timate tensile strength of pulsed current micro plasma arc welded Inconel 625 nickel alloy. Four factors, five levels, central composite rotatable design matrix is used to op- timize the number of experiments. The mathematical models have been developed by response surface method. The adequacy of the models is checked by analysis of vari- ance technique. By using the developed mathematical models, grain size and ultimate tensile strength of the joints can be predicted with 99% confidence level. Contour plots are drawn to study the interaction effect of pulsed current micro plasma arc welding parameters on fusion zone grain size and ultimate tensile strength of Inconel 625 weld joints.

关键词： Pulsed current micro plasma arc welding ANOYA Response surface method: Inconel 625

Effect of Post Cryorolling Treatments on microstructural and mechanical Behaviour of Ultrafine Grained Al-mg-Si Alloy

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Journal of materials Science & Technology 2014年第10期30卷 998-1005页

作者： P.nageswara rao Dharmendra Singh R.Jayaganthan Department of metallurgical and materials Engineering Indian Institute of Technology Roorkee

To investigate the effect of post cryorolling treatments on simultaneous enhancement in strength and ductility of ultrafine grained material （UFG）, AI 6061 alloy was subjected to cryorolling followed by warm rolling （CR ＋ WR） and compared with cryorolling followed by short annealing （CR ＋ SA） at the same temperature. Transmission electron microscopy （TEm） was used to characterize the microstructural features of the processed material. The mechanical properties were investigated through Vickers hardness testing and tensile testing at room temperature. TEm, X-ray diffraction （XRD） and differential scanning calorimetry （DSC） were used to investigate the precipitation evolution in UFG material. Results indicated that the alloy subjected to CR ＋ WR has shown improved mechanical properties （114 HV, ultimate tensile strength （UTS）： 350 mPa） as compared to that in the case of CR ＋ SA （105 HV, UTS： 285 mPa）. The size of the precipitates observed in CR ＋ WR sample after peak ageing treatment is finer than that of peak aged CR ＋ SA sample. The UTS of peak aged CR ＋ WR sample （UTS： 390 mPa） was found to be higher than that of peak aged CR ＋ SA sample （UTS： 355 mPa）, without decrease in ductility.

关键词： Aluminium alloy Cryorolling Warm rolling Short annealing mechanical properties Differential scanning calorimetry (DSC)

The Role of Vanadia for the Selective Oxidation of Benzyl Alcohol over Heteropolymolybdate Supported on Alumina

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催化学报 2011年第11期32卷 1719-1726页

作者： Pasupulet Siva nageswara rao Kasanneni Tirumala Venkateswara rao Potharaju S. SAI PRASAD Nakka LINGAIAH Catalysis Laboratory Inorganic and Physical Chemistty Division Indian Institute of Chemical Technology Hyderabad 500 607 lndia

A series of 12-molybdophosphoric acid (mPA) supported on V2O5 dispersed γ-Al2O3 catalysts with different vanadia loadings were prepared by impregnation and characterized by N2 adsorption-desorption, X-ray diffraction, temperature-programmed reduction, in situ laser Raman spectroscopy, UV-Vis diffused reflectance spectroscopy, scanning electron microscopy, and temperature-programmed desorption of NH3 techniques. Their catalytic activities were evaluated for the vapor phase aerobic oxidation of benzyl alcohol. The catalysts exhibited high catalytic activity and the conversion of benzyl alcohol depended on the vanadia content while the catalyst with 15 wt% V2O5 content showed optimum activity. The characterization results suggest the presence of well-dispersed V2O5 and partially disintegrated Keggin ions of mPA on the support. In situ Raman studies showed a reduced mo(IV) species when the catalysts were calcined at high temperatures. The high oxidation activity of the catalysts is related to the synergistic effect between mPA and V2O5.

关键词： molybdophosphoric acid vanadia alumina oxidation benzyl alcohol

microstructures and impact toughness behavior of Al 5083 alloy processed by cryorolling and afterwards annealing

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International Journal of minerals,metallurgy and materials 2013年第8期20卷 759-769页

作者： Dharmendra Singh P.nageswara rao R.Jayaganthan Department of metallurgical and materials Engineering Indian Institute of Technology RoorkeeRoorkee-247667India

The influence of rolling at liquid nitrogen temperature and annealing on the microstructure and mechanical properties of Al 5083 alloy was studied in this paper. Cryorolled samples of Al 5083 show significant improvements in strength and hardness. The ultimate tensile strength increases up to 340 mPa and 390 mPa for the 30% and 50% cryorolled samples, respectively. The cryorolled samples, with 30% and 50% reduction, were subjected to Charpy impact testing at various temperatures from 190℃ to 100℃. It is observed that increasing the percentage of reduction of samples during cryorolling has significant effect on decreasing impact toughness at all temperatures by increasing yield strength and decreasing ductility. Annealing of samples after cryorolling shows remarkable increment in impact toughness through recovery and recrystallization. The average grain size of the 50% cryorolled sample （14 μm） after annealing at 350℃ for 1 h is found to be finer than that of the 30% cryorolled sample （25 μm）. The scanning electron microscopy （SEm） analysis of fractured surfaces shows a large-size dimpled morphology, resembling the ductile fracture mechanism in the starting material and fibrous structure with very fine dimples in cryorolled samples corresponding to the brittle fracture mechanism.

关键词： aluminum alloys cryorolling annealing microstructure impact toughness recovery recrystallization

Development and Characterization of Elite Doubled Haploid Lines from Two Indica Rice Hybrids

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Rice science 2015年第6期22卷 290-299页

作者： Rukmini mISHRA Gundimeda Jwala Narashima rao Ravi nageswara rao Pankaj KAUSHAL Crop Improvement Division Central Rice Research Institute Indian Grassland and Fodder Institute

Despite significant yield advantage over inbred rice, the adoption rate of hybrid rice in India is very low due to the high seed cost and poor quality of the produce. To alleviate the problem, we initiated a doubled haploid （DH） breeding approach to develop new lines from two elite indica rice hybrids （CRHR5 and CRHR7） through rapid fixation of homozygosity in the recombinants. In vitro culture of the rice anthers resulted in 243 and 186 fertile DH lines of CRHR5 and CRHR7, respectively. Flow cytometric and pollen fertility analyses confirmed the DH ploidy status of the regenerations. morpho-agronomic evaluation revealed 100% uniformity and stability for all the characters in the DH lines of both hybrids. Nineteen promising DH lines of each hybrid were advanced to A2 generation for yield evaluation. The yield levels of the DH lines ranged from 5 097-6 965 kg/hm^2 for CRHR5 and 5 141-7 235 kg/hm^2 for CRHR7, which were at par or higher than the parental hybrids. Physico-chemical characterization and cooking quality analyses revealed significant and acceptable values for grain length and width, alkali spreading value, amylose content and water uptake ratio of the selected DH lines. Three DH lines, CR5-10, CR5-49, CR5-61 from CRHR5, and four DH lines, CR7-5, CR7-7, CR7-12 and CR7-52 from CRHR7, showed significant grain yield and quality characteristics and have been recommended for multi-location trials for subsequent release as new indica doubled haploid rice varieties.

关键词： anther culture doubled haploid indica rice hybrid

Predicting the success rate of a start-up using LSTm with a swish activation function

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Journal of Control and Decision 2022年第3期9卷 355-363页

作者： Ramakrishna Allu Venkata nageswara rao Padmanabhuni Department of Computer Science and Engineering GITAM(Deemed to be university)VisakhapatnamAndhra PradeshIndia

The researchers emphasised more small-scale start-ups which required improvement in the economy decreased the failure rate by avoiding the valuable *** resources were required to be used without wasting them lead to the development of the economy and reduces the rate of ***,to minimise resource wastage and to avoid the risk of failure the researchers considered certain factors that affected the failure and success of smallscale *** present research uses the Crunch Base dataset that predicts the success or failure of a start-up by using the Long Short Term memory(LSTm).The LSTm unit Recurrent Neural Network(RNN)uses the Swish activation function in Feed Forward Neural(FFN)Network for the *** proposed LSTm obtained better accuracy of 71.64%when compared with existing methods such as RNN that attained 65.67%and Artificial Neural Network(ANN)of 69.7%.

关键词： Crunch base dataset gross domestic product long short term memory recurrent neural network start-up companies

Optimization and validation of a fast RP-HPLC method for the determination of dobutamine in rat plasma:Pharmacokinetic studies in healthy rat subjects

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Journal of Pharmaceutical Analysis 2013年第6期3卷 434-439页

作者： Ramesh Thippani nageswara rao Pothuraju nageswara rao Ramisetti Saida Shaik Department of Chemistry National Institute of Technology Analytical Chemistry Division IICT

A novel isocratic reverse phase high performance liquid chromatography （RP-HPLC） with photo diode array （PDA） detection method for the determination of dobutamine （DBT） in rat plasma was developed and validated after optimization of various chromatographic conditions and other experimental parameters. Homoveratrylamiue was used as an internal standard. methanol was used as the extracting solvent for the preparation of plasma samples. Samples were separated on a Symmetry C18 （250ram x4.6mm i.d., 5 pro） analytical column. Acetonitrile and 15ram potassium dihydrogen phosphate （pH 5.0 with 0.3% TEA）（20：80, v/v） was used. The column oven temperature was optimized at 35 ~C and the flow rate was 0.8 mL/min. The detection wavelength was fixed at 230 nm for entire analysis. The calibration curve was found to be linear over the concentration range of 50-2000 ng/mL （ra=0.9992）. The limit of quantification （LOQ） of the method was 50 ng/mL. The % RSD values of accuracy and precision values for intra and inter days were 〈 15% at quality control （QC） concentrations. Recovery, stability and robustness were studied within the acceptable range according to ICH guidelines. The method was efficiently applied to a pharmacokinetic study in healthy Wistar rats.

关键词： Dobutamine RP-HPLC Validation Rat plasma Pharmacokinetics

modeling of aggregation kernels for fluidized beds using discrete particle model simulations

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Particuology 2014年第2期12卷 134-144页

作者： nageswara rao Narni mirko Peglow Gerald Warnecke Jitendra Kumar Stefan Heinriche J.A.m.Kuipers Department of mathematics Rajiv Gandhi University of Knowledge TechnologiesGachibowliHyderabad 500032India Institute for Process Engineering Otto-von-Guericke-University MagdeburgUniversitatsplatz 2D-39106 MagdeburgGermany Institute for Analysis and Numerics Otto-von-Guericke-University MagdeburgUniversitatsplatz 2D-39106 MagdeburgGermany Department of mathematics ⅡT KharagpurIndia Institute of Solids Process Engineering and Particle TechnologyHamburg University of TechnologyHamburgGermany Eindhoven University of Technology-SmR P.O.Box 5135600 MB EindhovenThe Netherlands

Aggregation is one of the many important processes in chemical and process engineering. Several researchers have attempted to understand this complex process in fluidized beds using the macro-model of population balance equations （PBEs）. The aggregation kernel is an effective parameter in PBEs, and is defined as the product of the aggregation efficiency and collision frequency functions. Attempts to derive this kernel have taken different approaches, including theoretical, experimental, and empirical techniques. The present paper calculates the aggregation kernel using micro-model computer simulations, i.e., a discrete particle model. We simulate the micro-model without aggregation for various initial conditions, and observe that the collision frequency function is in good agreement with the shear kernel. We then simulate the micro-model with aggregation and calculate the aggregation efficiency rate.

关键词： Aggregation kernelsmulti-phase flowCollision frequency functionAggregation efficiency rateBed parameter

Highly sensitive assay for the determination of therapeutic peptide desmopressin in human plasma by UPLC–mS/mS

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Journal of Pharmaceutical Analysis 2017年第3期7卷 196-202页

作者： Shiva Kumar Gudlawar nageswara rao Pilli Sridhar Siddiraju Jaya Dwivedi Department of Chemistry Banasthali VidyapeethJaipur 304022India Wellquest Clinical Research Laboratories RamanthapurHyderabad 500013India Department of Pharmaceutical Chemistry Malla Reddy College of PharmacyMaisammagudaSecunderabad 5000100India

An analytical method based on ultra-performance liquid chromatography with positive ion electrospray ionization(ESI) coupled with tandem mass spectrometry(UPLC–mS/mS) was developed and validated for the determination of therapeutic peptide desmopressin in human plasma. A desmopressin stable labeled isotope(desmopressin d_8) was used as an internal standard. Analyte and the internal standard were extracted from200 μL of human plasma via solid-phase extraction technique using Oasis WCX cartridges. The chromatographic separation was achieved on an Aquity UPLC HSS T3 column by using a gradient mixture of methanol and 1 m m ammonium formate buffer as the mobile phase. The calibration curve obtained was linear(r^2≥0.99)over the concentration range of 1.01–200 pg/m L. method validation was performed as per FDA guidelines and the results met the acceptance criteria. The results of the intra-and inter-day precision and accuracy studies were well within the acceptable limits. The proposed method was successfully applied to pharmacokinetic studies in humans.

关键词： Desmopressin Solid-phase extraction (SPE) Ultra performance liquid chromatography–tandem mass spectrometry method validation Pharmacokinetics