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Polytypic transformations of aluminum hydroxide: A mechanistic investigation

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Particuology 2012年第3期10卷 359-364页

作者： Thimmasandra narayan Ramesh Centre for Advanced Materials and Department of Chemistry Tumkur University

The diffusion of ammonia vapors into a solution of aluminum nitrate or ferric nitrate results in the precipitation of their respective hydroxides and oxyhydroxides. Polymorphic phase formation of aluminum hydroxide is controlled by the rate of crystallization. The PXRD patterns of products obtained via vapor phase diffusion revealed that poorly ordered aluminum hydroxide is formed during the initial stages of crystallization. After 8 days, the formation of the bayerite phase of aluminum hydroxide was observed. Upon prolonged exposure to ammonia vapors, bayerite was transformed into gibbsite. The infrared spectrum of the product confirmed the presence of different polytypic phases of aluminum hydroxide. The results demonstrated that the crystal structure of metal hydroxides is controlled by the rate of crystallization, nature of the metal ion, site selectivity and specificity and preparative conditions.

关键词： Vapor phase diffusionAluminum hydroxideGibbsiteBayeritePolytypism

Workability Studies in Forming of Sintered Fe-0.35CPowder Metallurgy Preform During Cold Upsetting

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Journal of Iron and Steel Research International 2011年第12期18卷 71-78页

作者： S narayan A Rajeshkannan School of Engineering and Physics Faculty of ScienceTechnology and EnvironmentUniversity of the South Pacific(Laucala Campus)

An experimental investigation on the workability behaviour of sintered Fe-0.35C steel preforms under cold upsetting,have been studied in order to understand the influence of aspect ratio and lubrication condition on the workability *** above mentioned powder metallurgy sintered preform with constant initial theoretical density of 84% of different aspect ratios,namely,0.4 and 0.6 respectively were prepared using a suitable die-set assembly on a 1 MN capacity hydraulic press and sintered for 90 min at 1200 ℃.Each sintered preform was cold upset under nil/no and graphite frictional constraint,*** the condition of triaxial stress densification state,axial stress,hoop stress,hydrostatic stress,effective stress and formability stress index against axial strain relationship was established and presented in this *** more,attained density was considered to establish formability stress index and various stress ratio parameters behaviour.

关键词： powder metallurgy failure analysis plastic behaviour workability

Influence of Carbon Content on Strain Hardening Behaviour of Sintered Plain Carbon Steel Preforms

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Journal of Iron and Steel Research International 2011年第9期18卷 33-40页

作者： S narayan A Rajeshkannan Mechanical Engineering The University of the South PacificLaucala Campus

Complete experimental investigation on the instantaneous strain hardening behaviour of powder metallurgy （P/M） preforms of pure iron, Fe 0.35%C, Fe-0.75%C and Fe-1.1%C was carried out. The strain hardening be haviour of the above-mentioned P/M sintered steel preforms with aspect ratio of 0.4 under triaxial stress state condition was determined by cold upsetting under nil/no and graphite lubricant conditions. The instantaneous strain hardening value （ni）, strength coefficient （Ki）, and the stress as a function of strain and densification were obtained and analyzed. Furthermore, a relation was obtained from a semi-log plot of stress against relative density and analyzed to study the hardening behaviour owing to densification as stress was a function of induced strain as well as densification in the P/M materials.

关键词： strain hardening exponent density hardening exponent strength coefficient densification triaxial stress

BORON:an ultra-lightweight and low power encryption design for pervasive computing

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Frontiers of Information Technology & Electronic Engineering 2017年第3期18卷 317-331页

作者： Gaurav BANSOD narayan PISHAROTY Abhijit PATIL Pune Institute of Computer Technology Pune 411043India Glocal University Saharanpur 247121India Symbiosis Institute of Technology Pune 412115India

We propose an ultra-lightweight, compact, and low power block cipher BORON. BORON is a substitution and permutation based network, which operates on a 64-bit plain text and supports a key length of 128/80 bits. BORON has a compact structure which requires 1939 gate equivalents(GEs) for a 128-bit key and 1626 GEs for an 80-bit key. The BORON cipher includes shift operators, round permutation layers, and XOR operations. Its unique design helps generate a large number of active S-boxes in fewer rounds, which thwarts the linear and differential attacks on the cipher. BORON shows good performance on both hardware and software platforms. BORON consumes less power as compared to the lightweight cipher LED and it has a higher throughput as compared to other existing SP network ciphers. We also present the security analysis of BORON and its performance as an ultra-lightweight compact cipher. BORON is a well-suited cipher design for applications where both a small footprint area and low power dissipation play a crucial role.

关键词： Lightweight cryptography SP network Block cipher Internet of Things(Io T) Encryption Embedded security

Mercury emissions and partitioning from Indian coal-fired power plants

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Journal of Environmental Sciences 2021年第2期33卷 28-33页

作者： Hridesh Agarwalla Rabi narayan Senapati Tarit Baran Das Coal Minerals&Heauy Metal Research Group CSIR-Central Institute of Mining and Furl ResearchDhcmbad-82810India

In India coal combustion is the single largest source of emission of mercury which is a widespread persistent global toxicant,travelling across international borders through air and *** a party to the Minamata convention,India aims to monitor and reduce Hg emissions and stricter norms are introduced for mercury emissions from power plants(30μg/Nm 3 for flue gas in stack).This paper presents the results obtained during the experimental studies performed on mercury emissions at four coal-fired and one lignite-fired power plants in *** mercury concentration in the feed coal varied between 0.12-0.27 mg/*** the mercury mass balance,significant proportion of feed coal mercury has been found to be associated with fly ash,whereas bottom ash contained very low mercury.80%-90%of mercury was released to air through stack ***,for circulating fluidised bed boiler burning lignite,about 64.8%of feed mercury was found to get captured in the fly ash and only 32.4%was released to *** mercury emission factor was found to lie in the range of 4.7-15.7 mg/GJ.

关键词： Coal combustion Emission Mercury Flue gas Thermal power plant

Stochastic Collocation on Unstructured Multivariate Meshes

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Communications in Computational Physics 2015年第6期18卷 1-36页

作者： Akil narayan Tao Zhou Scientific Computing and Imaging Institute University of UtahSalt Lake CityUT 84112USA LSEC Institute of Computational Mathematics and Scientific/Engineering ComputingAMSSthe Chinese Academy of SciencesBeijingChina

Collocation has become a standard tool for approximation of parameterized systems in the uncertainty quantification(UQ)*** for leastsquares regularization,compressive sampling recovery,and interpolatory reconstruction are becoming standard tools used in a variety of *** of a collocation mesh is frequently a challenge,but methods that construct geometrically unstructured collocation meshes have shown great potential due to attractive theoretical properties and direct,simple generation and *** investigate properties of these meshes,presenting stability and accuracy results that can be used as guides for generating stochastic collocation grids in multiple dimensions.

关键词： Stochastic collocation unstructured methes least-squares compressive sampling least interpolation

Temporal cues and the effect of their enhancement on speech perception in older adults——A scoping review

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Journal of Otology 2016年第3期11卷 95-101页

作者： Hemanth narayan Shetty All India Institute of Speech and Hearing

Temporal envelope is a low frequency amplitude modulation conveying segmental and suprasegmental information during speech ***,we seldom find ourselves in completely quiet listening environments and noise,commonly found in the surrounding environment,obscures both the fine structure cues and partly the temporal envelope cues in *** temporal content of speech emanating from noise is often enough to convey required information in normal hearing ***,the case is different in older adults(with and without hearing loss) who lack such capabilities due to the impairment in temporal *** calls attention of a researcher to delineate the importance of temporal enhancement of speech in improving speech *** are many temporal envelope strategies available in the literature,but each one has its own *** envelope enhancement by a deep band modulation(DBM) is found to be beneficial for those individuals who have had a temporal processing *** reason could be attributed to the 15 dB enhancement in the temporal envelope bandwidth between 3 and 30 Hz,extracted from each channel,which significantly increases the modulation depth such that masking of a consonant by a vowel is ***,output of deep band modulated speech is rescaled such that its duration increases and it provides relatively easy access to the word of the ***,in the near future,with more experiments related to DBM algorithm,it can be utilized in the rehabilitative devices to lessen the impact of the temporal processing impairment.

关键词： Temporal Envelope Modulation Older adults

Distributional Sensitivity for Uncertainty Quantification

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Communications in Computational Physics 2011年第6期10卷 140-160页

作者： Akil narayan Dongbin Xiu Department of Mathematics Purdue University150 N.University StreetWest LafayetteIN 47904USA

In this work we consider a general notion of distributional sensitivity,which measures the variation in solutions of a given physical/mathematical system with respect to the variation of probability distribution of the *** is distinctively different from the classical sensitivity analysis,which studies the changes of solutions with respect to the values of the *** general idea is measurement of sensitivity of outputs with respect to probability distributions,which is a well-studied concept in related *** adapt these ideas to present a quantitative framework in the context of uncertainty quantification for measuring such a kind of sensitivity and a set of efficient algorithms to approximate the distributional sensitivity numerically.A remarkable feature of the algorithms is that they do not incur additional computational effort in addition to a one-time stochastic ***,an accurate stochastic computation with respect to a prior input distribution is needed only once,and the ensuing distributional sensitivity computation for different input distributions is a post-processing *** prove that an accurate numerical model leads to accurate calculations of this sensitivity,which applies not just to slowly-converging Monte-Carlo estimates,but also to exponentially convergent spectral *** provide computational examples to demonstrate the ease of applicability and verify the convergence claims.

关键词： Uncertainty quantification epistemic uncertainty distributional sensitivity generalized polynomial chaos

Effect of disturbance on biomass,production and carbon dynamics in moist tropical forest of eastern Nepal

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Forest Ecosystems 2016年第3期3卷 221-230页

作者： Tilak Prasad Gautam Tej narayan Mandal Department of Botany Mahendra Morang Adarsha Multiple CampusTribhuvan University Department of Botany Post Graduate Campus Tribhuvan University

Background： Forest biomass is helpful to assess its productivity and carbon （C） sequestration capacity. Several disturbance activities in tropical forests have reduced the biomass and net primary production （NPP） leading to climate change. Therefore, an accurateestimation of forest biomass and C cycling in context of disturbances is required for implementing REDD （Reducing Emissions from Deforestation and Forest Degradation） policy. Methods： Biomass and NPP of trees and shrubs were estimated by using allometric equations while herbaceous biomass was estimated by harvest method. Fine root biomass was determined from soil monolith. The C stock in vegetation was calculated by multiplying C concentration to dry weight. Results： Total stand biomass （***-1） in undisturbed forest stand （US） was 960.4 while in disturbed forest stand （DS） it was 449.1. The biomass （***-1） of trees, shrubs and herbs in US was 948.0, 4.4 and 1.4, respectively, while in DS they were 438.4, 6.1 and 1.2, respectively. Total NPP （***-1） was 26.58 （equivalent to 12.26 Mg ***-1） in US and 14.91 （6.88 Mg ***-1） in DS. Total C input into soil through litter plus root turnover was 6.78 and 3.35 ***-1 in US and DS, respectively. Conclusions： Several disturbance activities resulted in the significant loss in stand biomass （53 %）, NPP （44 %）, and C sequestration capacity of tropical forest vegetation is far greater than that returned to the soil n eastern Nepal. The net uptake of carbon by the by the turnover of fine root and litter. Therefore, both stands of present forest act as carbon accumulating systems. Moreover, disturbance reflects higher C emissions which can be reduced by better management.

关键词： Tropical forest Disturbance Biomass Production Carbon cycling Nepa