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CURING KINETICS AND THERMAL STABILITY OF EPOXY BLENDS CONTAINING PHOSPHOROUS-OXIRANE WITH AROMATIC AMIDE-AMINE AS CURING AGENTS

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Chinese Journal of Polymer Science 2012年第5期30卷 694-704页

作者： Geeta durga A.K.Narula School of Basic and Applied Sciences Guru Gobind Singh Indraprastha University

This article describes the synthesis of a series of aromatic amide-amines and their potential use as epoxy hardeners. These amines were synthesized by the reaction of L-phenylalanine （PA） with diamines of different structures i.e. 1,4- phenylene diamine （PD）, 1,5-diamino naphthalene （N）, 4,4＇-（9-fluorenyllidene）-dianiline （F）, 4,4＇-diaminodiphenyl sulphide （DS） and 3,4＇-oxydianiline （O） in a stoichiometric ratio （I ：1）. Structural characterization of synthesized amide-amines was done with the help of elemental analysis and spectroscopic techniques viz. FT-IR, 1H-NMR and 13C-NMR. An epoxy blend was prepared by mixing tris（glycidyloxy） phosphine oxide （TGPO） with conventional epoxy i.e. diglycidyl ether of bisphenol-A （DGEBA） in an equivalent ratio of 2：3 to incorporate phosphorous into the main chain. The curing kinetics of the epoxy blend with synthesized aromatic amide-amines was investigated by non-isothermal DSC technique using multiple heating rate method （5, 10, 15 and 20 K/min.）. The activation energies were determined by fitting the experimental data into Kissinger and Ozawa kinetic models. The activation energies obtained through Ozawa method were slightly higher than those of Kissinger method but were comparable. However, both the energies were found to be dependent on the structure of amines. The thermal stability and weight loss behavior of isothermally cured thermosets were also investigated using thermogravimetric analysis （TGA） in nitrogen atmosphere. All the samples showed improved thermal stability in terms of char yield than using only amines as hardeners.

关键词： Phosphorylated epoxy Amide-Amines Curing kinetics Char yield Thermal stability.

Variability and divergence in horsegram (Dolichos uniflorus)

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Journal of Arid Land 2012年第1期4卷 71-76页

作者： Kanaka K durga Seed Research & Technology Centre RajendranagarHyderabadAPIndia

Horsegram is an important and unexploited tropic and sub-tropic legume crop grown mostly in dry land agriculture. The study involving 23 cultivars of horsegram （Dolichos uniflorus） was conducted at the Seed Research ＆ Technology Centre in Rajendranagar, Hyderabad, India during the early spring seasons of 2008 and 2009 to assess the nature and magnitude of variability in the existing species and also to identify diverse parents for use in further breeding programmes. The results indicated significant differences among the 23 cultivars for all characters studied, indicating the presence of sufficient genetic variation. High variability and heritability coupled with high genetic advance were reported for seed yield per plant and pod hulm per plant, indicating additive gene action and a possible scope for the improvement of these characters. Mahalanobis D2 statistics grouped all the 23 cultivars of horsegram into six ,clusters. The maximum inter cluster distance （62.39） was noticed between cluster IV （HG 50） and cluster V （HG 11）. The maximum Jntra cluster distance ranged from 0 （clusters III, IV, V and VI） to 15.17 （cluster I）, indicating that the genotypes in these clusters were relatively more diverse than the genotypes within other clusters. Seed yield per plant contributed the maximum （33.20%） to the genetic divergence.

关键词： horsegram Dolichos uniflorus variability divergence genotype yield components seed quality parameters

Study of Electronic Density of States: Zintl Alloys

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Communications in Theoretical Physics 2011年第2期55卷 362-364页

作者： Ashwani Kumar durga Prasad Ojha Post Graduate Department of Physics Andhra Loyola College

In the present work the electronic density of states of liquid,viz.,Zintli alloys,have been studied only at the composition of their maximum resistivity to have an elementary idea about the behaviors of the alloys with respect to nearly free electron *** study reveals that the anomalous electronic behavior of liquid Li-Pb,Na-Pb,Li-Sn,and Na-Sn can be attributed to the preferential ordering of unlike atoms.

关键词： alloys thermodynamics of solutions density of states phase diagram

Mechanical memory operations in piezotransistive GaN microcantilevers using Au nanoparticleenhanced photoacoustic excitation

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Microsystems & Nanoengineering 2022年第1期8卷 161-174页

作者： Ferhat Bayram durga Gajula Digangana Khan Goutam Koley Holcombe Department of Electrical and Computer Engineering Clemson UniversityClemsonSC 29634USA School of Electrical and Computer Engineering Georgia Institute of TechnologyAtlantaGA 30332USA

Nonlinear oscillations in micro-and nanoelectromechanical systems have emerged as an exciting research area in recent years due to their promise in realizing low-power,scalable,and reconfigurable mechanical memory and logic ***,we report ultralow-power mechanical memory operations utilizing the nonlinear oscillation regime of GaN microcantilevers with embedded piezotransistive AlGaN/GaN heterostructure field effect transistors as highly sensitive deflection *** between the high and low oscillatory states of the nonlinear oscillation regime was demonstrated using a novel phase-controlled opto-mechanical excitation setup,utilizing a piezo actuator and a pulsed laser as the primary and secondary excitation sources,***-based photoacoustic excitation was amplified through plasmonic absorption in Au nanoparticles deposited on a ***,the minimum switching energy required for reliable memory operations was reduced to less than a picojoule(pJ),which translates to one of the lowest ever reported,when normalized for mass.

关键词： excitation operations cantilever

Source Code Prioritization Using Forward Slicing for Exposing Critical Elements in a Program

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Journal of Computer Science & Technology 2011年第2期26卷 314-327页

作者： Mitrabinda Ray Kanhaiya lal Kumawat durga Prasad Mohapatra Department of Computer Science and Engineering National Institute of Technology

Even after thorough testing, a few bugs still remain in a program with moderate complexity. These residual bugs are randomly distributed throughout the code. We have noticed that bugs in some parts of a program cause frequent and severe failures compared to those in other parts. Then, it is necessary to take a decision about what to test more and what to test less within the testing budget. It is possible to prioritize the methods and classes of an object-oriented program according to their potential to cause failures. For this, we propose a program metric called influence metric to find the influence of a program element on the source code. First, we represent the source code into an intermediate graph called extended system dependence graph. Then, forward slicing is applied on a node of the graph to get the influence of that node. The influence metric for a method m in a program shows the number of statements of the program which directly or indirectly use the result produced by method m. We compute the influence metric for a class c based on the influence metric of all its methods. As influence metric is computed statically, it does not show the expected behavior of a class at run time. It is already known that faults in highly executed parts tend to more failures. Therefore, we have considered operational profile to find the average execution time of a class in a system. Then, classes are prioritized in the source code based on influence metric and average execution time. The priority of an element indicates the potential of the element to cause failures. Once all program elements have been prioritized, the testing effort can be apportioned so that the elements causing frequent failures will be tested thoroughly. We have conducted experiments for two well-known case studies -- Library Management System and Trading Automation System -- and successfully identified critical elements in the source code of each case study. We have also conducted experiments to compar

关键词： program slice extended system dependence graph influence of a class test priority

Investigation of structural,magnetic and optical properties of rare earth substituted bismuth ferrite

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Journal of Rare Earths 2013年第4期31卷 370-375页

作者： T.durga Rao T.Karthik Saket Asthana Advanced Functional Materials Laboratory Department of PhysicsIndian Institute of Technology Hyderabad Department of Materials Science and Engineering Indian Institute of Technology Hyderabad

Polycrystalline BiFeO3 and rare earth substituted ***3 （BRFO, R=Y, Ho and Er） compounds were prepared by rapid solid state sintering technique. Structural phase analysis indicated that all the compounds stabilized in rhombohedral structure （R3c space group） and a small orthorhombic phase fraction was observed in BRFO compounds. From the Raman spectra results, the changes in the phonon frequencies （A1） and line widths suggested lattice distortion in the BRFO compounds as was evidenced in the XRD analysis. Compared to the linear variation of magnetization with magnetic field （M-H） shown by BFO, an obvious M-H loop was observed in BRFO compounds which could be due to the suppression of space modulated spin structure and was explained on the basis of weak ferromagnetism and field induced spin reorientation. UV-Vis spectroscopy evidenced a change in local FeO6 envi- ronment due to shift in the 6Alg→4T2g energy transition band. BRFO compounds with improved remnant magnetization and coercive field are applicable for magnetoelectric devices.

关键词： structural distortion spin-reorientation G-type antiferromagnet rare earths

Attention boosted autoencoder for building energy anomaly detection

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Energy and AI 2023年第4期14卷 479-489页

作者： durga Prasad Pydi S.Advaith Department of Mechanical Engineering Indian Institute of Technology MadrasChennai600036India

Significant energy savings can be realised from buildings if deviations from the usual operating conditions are detected early,and appropriate measures are *** anomaly detection techniques automate identifying such instances by leveraging the high dimensional data collected from the installed smart *** allow for dimensionality reduction and also model the underlying data ***,these models treat features as independent *** contrast,the current work investigates an attention mechanism with an autoencoder to include the correlations among the *** value addition from the attention mechanism is demonstrated by comparing the model’s reconstruction ability with an ANN-based autoencoder on synthetic *** study identifies that adding an attention layer enables the encoder–decoder architecture to be robust to outliers in training data,thereby reducing the preprocessing ***,the model is tested on a real-world dataset,and the attention maps generated from the model are used to interpret the correlations among the features and across the time dimension,thereby establishing a human-interpretable way to understand the reconstruction from the model.

关键词： Artificial intelligence UN Sustainable Development Goals Interpretable model Multivariate time series HVAC

A review and critical appraisal of central axis flaps in axillary and elbow contractures

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Burns & Trauma 2017年第2期5卷 85-94页

作者： durga Karki Rajeev B. Ahuja Department of Burns Plastic and Maxillofacial Surgery VM Medical College and Safdarjung Hospital New Delhi 110029 India Department of Burns and Plastic Surgery Lok Nayak Hospital and associated Maulana Azad Medical College New Delhi 110002 India

Contractures of the axilla and elbow can produce a significant impact on quality of life by reducing the ability to perform activities of daily living. Varieties of techniques are available for resurfacing defects following contracture release but graft or flap loss, donor-site morbidity, esthetics, and recurrences are still challenges for reconstructive surgeons. Central axis 'propeller' flaps based on a random, subcutaneous pedicle were first described for axillary and elbow contractures to deploy the unburnt skin of axillary dome in type Ⅰ and Ⅱ contractures (Kurtzman and Stern) by moving them 90° to straddle the contracting bands. This strategy provided better esthetics and avoided prolonged splinting. Over more than two decades, there have been several design modifications of these flaps with extended applications to cubital fossa. A comprehensive review of published literature on the topic is presented to discuss classifications, design modifications, and applications of such flaps in managing axillary and elbow contractures.

关键词： Central axis flap Subcutaneous pedicled flap Propeller flap Axillary contracture Elbow contracture

Effects of economic factors on median list and selling prices in the *** market

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Data Science and Management 2023年第4期6卷 199-207页

作者： durga Vaidynathan Parthajit Kayal Moinak Mait Madras School of Economics(MSE) Chennai600025India Independent Researcher Kolkata711112India

This study investigates the effects of key economic factors on the median list price and median selling price in the *** *** economic factors such as interest rates,unemployment rates,inflation rates,real gross domestic product,money supply,mortgage rate,Standard&Poor’s(S&P)500,and government expenditure are investigated to understand their relationships with housing *** econometric models are typically used for housing market analysis;however,advancements in data science and machine learning allow these relationships to be examined more *** study employs a decision tree regressor,k-nearest neighbors,random forest,and gradient boosting to enhance analysis accuracy and feature selection,thus enriching literature pertaining to machine learning in the housing market *** significance of housing market data as an indicator of economic growth is emphasized,and its effect on the overall economy,consumer spending,investment patterns,and financial stability is *** utilizing a robust dataset and performing rigorous preprocessing,this study aims to provide valuable insights for policymakers,investors,and individuals involved in the housing sector.

关键词： Machine learning Economic factor Housing price Predictive modeling Data science