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Robust Adaptive Gain Higher Order Sliding Mode Observer Based Control-constrained Nonlinear Model Predictive Control for Spacecraft Formation Flying

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IEEE/CAA Journal of Automatica Sinica 2018年第1期5卷 367-381页

作者： Ranjith Ravindranathan nair Laxmidhar Behera Department of Electrical Engineering Indian Institute of TechnologyKanpur Kanpur-208 016India IEEE

This work deals with the development of a decentralized optimal control algorithm, along with a robust observer,for the relative motion control of spacecraft in leader-follower based formation. An adaptive gain higher order sliding mode observer has been proposed to estimate the velocity as well as unmeasured disturbances from the noisy position measurements.A differentiator structure containing the Lipschitz constant and Lebesgue measurable control input, is utilized for obtaining the estimates. Adaptive tuning algorithms are derived based on Lyapunov stability theory, for updating the observer gains,which will give enough flexibility in the choice of initial ***, it may help to cope with unexpected state jerks. The trajectory tracking problem is formulated as a finite horizon optimal control problem, which is solved online. The control constraints are incorporated by using a nonquadratic performance functional. An adaptive update law has been derived for tuning the step size in the optimization algorithm, which may help to improve the convergence speed. Moreover, it is an attractive alternative to the heuristic choice of step size for diverse operating conditions. The disturbance as well as state estimates from the higher order sliding mode observer are utilized by the plant output prediction model, which will improve the overall performance of the controller. The nonlinear dynamics defined in leader fixed Euler-Hill frame has been considered for the present work and the reference trajectories are generated using Hill-Clohessy-Wiltshire equations of unperturbed motion. The simulation results based on rigorous perturbation analysis are presented to confirm the robustness of the proposed approach.

关键词： Adaptive gain higher order sliding mode observer leader-follower formation nonlinear model predictive control spacecraft formation flying tracking control

Surface-Engineered Li4Ti5O12 Nanostructures for High-Power Li-Ion Batteries

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Nano-Micro Letters 2020年第2期12卷 235-245页

作者： Binitha Gangaja Shantikumar nair Dhamodaran Santhanagopalan Centre for Nanosciences and Molecular Medicine Amrita Vishwa Vidyapeetham

Materials with high-power charge–discharge capabilities are of interest to overcome the power limitations of conventional Li-ion *** this study,a unique solvothermal synthesis of Li4Ti5O12 nanoparticles is proposed by using an off-stoichiometric precursor ratio.A Li-deficient off-stoichiometry leads to the coexistence of phaseseparated crystalline nanoparticles of Li4Ti5O12 and TiO2 exhibiting reasonable high-rate ***,after the solvothermal process,an extended aging of the hydrolyzed solution leads to the formation of a Li4Ti5O12 nanoplate-like structure with a self-assembled disordered surface layer without crystalline *** Li4Ti5O12 nanoplates with the disordered surface layer deliver ultrahighrate performances for both charging and discharging in the range of 50–300C and reversible capacities of 156 and 113 mAh g−1 at these two rates,***,the electrode exhibits an ultrahigh-charging-rate capability up to 1200C(60 mAh g−1;discharge limited to 100C).Unlike previously reported high-rate half cells,we demonstrate a high-power Li-ion battery by coupling Li4Ti5O12 with a high-rate LiMn2O4 *** full cell exhibits ultrafast charging/discharging for 140 and 12 s while retaining 97 and 66% of the anode theoretical capacity,***-(25℃),low-(−10℃),and high-(55℃)temperature cycling data show the wide temperature operation range of the cell at a high rate of 100C.

关键词： Ultrafast charging Li-ion battery Lithium titanate Off-stoichiometric synthesis Surface chemistry

Concurrent repletion of iron and zinc reduces intestinal oxidative damage in iron- and zinc-deficient rats

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World Journal of Gastroenterology 2007年第43期13卷 5707-5717页

作者： Sreedhar Bodiga Madhavan nair Krishnapillai Department of Biophysics National Institute of Nutrition Hyderabad 500007 Andhra Pradesh India

AIM： To understand the interactions between iron and zinc during absorption in iron- and zinc-deficient rats, and their consequences on intestinal oxidant-antioxidant balance. METHODS： Twenty-four weanling Wistar-Kyoto rats fed an iron- and zinc-deficient diet （〈 6.5 mg Fe and 4.0 mg Zn/kg diet） for 4 wk were randomly divided into three groups （n = 8, each） and orally gavaged with 4 mg iron, 3.3 mg zinc, or 4 mg iron ＋ 3.3 mg zinc for 2 wk. At the last day of repletion, 3 h before the animals were sacrificed, they received either 37 mBq of SSFe or ^65Zn, to study their localization in the intestine, using microautoradiography. Hemoglobin, iron and zinc content in plasma and liver were measured as indicators of iron and zinc status. Duodenal sections were used for immunochemical staining of ferritin and metallothionein. Duodenal homogenates （mitochondrial and cytosolic fractions）, were used to assess aconitase activity, oxidative stress, functional integrity and the response of antioxidant enzymes. RESULTS： Concurrent repletion of iron- and zinc-deficient rats showed reduced localization of these minerals compared to rats that were teated with iron or zinc alone; these data provide evidence for antagonistic interactions. This resulted in reduced formation of lipid and protein oxidation products and better functional integrity of the intestinal mucosa. Further, combined repletion lowered iron-associated aconitase activity and ferritin expression, but significantly elevated metallothionein and glutathione levels in the intestinal mucosa. The mechanism of interactions during combined supplementation and its subsequent effects appeared to be due to through modulation of cytosolic aconitase, which in turn influenced the labile iron pool and metallothionein levels, and hence reduced intestinal oxidative ***： Concurrent administration of iron and zinc corrects iron and zinc deficiency, and also reduces the intestinal oxidative damage associated with iron suppl

关键词： Iron Zinc Absorption Intestine Aconitase Ferritin Metallothionein Oxidative damage

Sammon Quadratic Recurrent Multilayer Deep Classifier for Legal Document Analytics

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Computers, Materials & Continua 2022年第8期72卷 3039-3053页

作者： Divya Mohan Latha Ravindran nair School of Engineering Cochin University of Science and TechnologyKeralaIndia

In recent years,machine learning algorithms and in particular deep learning has shown promising results when used in the field of legal *** legal field is strongly affected by the problem of information overload,due to the large amount of legal material stored in textual *** text processing is essential in the legal domain to analyze the texts of the court events to automatically predict smart *** an increasing number of digitally available documents,legal text processing is essential to analyze documents which helps to automate various legal domain *** document classification is a valuable tool in legal services for enhancing the quality and efficiency of legal document *** this paper,we propose Sammon Keyword Mapping-based Quadratic Discriminant Recurrent Multilayer Perceptive Deep Neural Classifier(SKM-QDRMPDNC),a system that applies deep neural methods to the problem of legal document *** SKM-QDRMPDNC technique consists of many layers to perform the keyword extraction and ***,the set of legal documents are collected from the *** the keyword extraction is performed using SammonMapping technique based on the distance *** the extracted features,Quadratic Discriminant analysis is applied to performthe document classification based on the likelihood ratio ***,the classified legal documents are obtained at the output *** process is repeated until minimum error is *** experimental assessment is carried out using various performance metrics such as accuracy,precision,recall,F-measure,and computational time based on several legal documents collected from the *** observed results validated that the proposed SKM-QDRMPDNC technique provides improved performance in terms of achieving higher accuracy,precision,recall,and F-measure with minimum computation time when compared to existing methods.

关键词： Legal document data analytics recurrent multilayer perceptive deep neural network sammon mapping quadratic discriminant analysis likelihood ratio test

Contribution of leaf growth on the disappearance of fungicides used on tea under south Indian agroclimatic conditions

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2009年第6期10卷 422-426页

作者： Chinnachamy KARTHIKA Narayanan nair MURALEEDHARAN United Planter's Association of South India (UPASI) Tea Research Institute Tea Research Foundation Nirar Dam B.P.O United Planter's Association of South India (UPASI) Tea Research Institute Tea Research FoundationNirar Dam B.P.O

The sprayed chemicals on tea leaves disappear over a period of time by the influence of rainfall elution, evaporation, growth dilution, and photodegradation. Influence of plant growth on the four fungicides (hexaconazole, propiconazole, tridemorph, and c) was studied to know the constructive loss of fungicides. The study shows that residues of fungicides sprayed on tea shoots got diluted by the growing process. The expansion of a leaf took 8 to 11 d and more than 50% of the fungicide residues were cleaned out during this leaf expansion period. Under south Indian agroclimatic condition, the fungicides are sprayed at an interval of 10 d, so it is safe that the tea is harvested on the 10th day of the application of fungicides.

关键词： Tea shoots Growth Dilution Fungicides Residue loss

Reconfigurable control as actuator fault-tolerant control design for power oscillation damping

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Protection and Control of Modern Power Systems 2020年第1期5卷 70-81页

作者： Digvijay V.nair MSR Murty Faculty of Science&Technology IFHE HYDERABADShankerpally Road501203 HyderabadIndia Dept.of EEE CMR College of Engineering&TechnologyMedchal Road501401 HyderabadIndia

This paper presents design of an self contained actuators unit in wide area damping control of power system in stabilizing system response for both nominal system condition and during actuator *** it is presented that use of multiple actuators in wide area control aid in improving damping in power system.A wide area damping controller feeding multiple actuators to satisfy multiple objectives in wide area damping control of power system is *** of infinity norm of closed loop transfer function of power system with wide area controller in feedback path&closed loop poles placement techniques are used in controller *** a reconfigurable control on the lines of fault hiding principle is added to the controller design to maintain system damping to pre-fault level in case of actuator faults.A reconfiguration component(RC)is activated on occurrence of actuator fault thereby reconfiguring system dynamics and redistributing wide area control signal among remaining active *** together with remaining active actuators and under same wide area damping controller maintains system damping to pre-fault level thereby preserving system dynamic *** the reconfigurable control design presented here no new actuators outside the unit of actuators designed for wide area damping control is *** makes for an self contained actuators unit in wide area damping control of power system both for nominal system condition and for system affected by actuator faults.A two area power system model is considered here for demonstrating effectiveness of designed robust damping controller with multiple outputs feeding multiple actuators in wide area control and illustrating the idea of self contained actuators unit for maintaining system damping in case of actuator faults.

关键词： Wide area control Robust damping controller Actuator fault Reconfigurable control Reconfiguration component Self contained actuators unit Power oscillations

Heavy Metal Accumulation in Medicinal Plants Collected from Environmentally Different Sites

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Biomedical and Environmental Sciences 2008年第4期21卷 319-324页

作者： JYOTI BARTHWAL SMITHA nair POONAM KAKKAR Herbal Research Section Industrial Toxicology Research Centre

Objective To estimate the heavy metal content in soil and selected medicinal plants procured from environmentally different sites of the same city. Methods Soil and plant samples of Abutilon indicum, Calotropis procera, Euphorbia hirta, Peristrophe bycaliculata, and Tinospora cordifolia were collected from 3 environmentally different sites of the city： heavy traffic area （HTA）, industrial area （IA）, and residential area （RA）. Pb by inductively coupled plasma emission spectrometry and compared Cd, Cr, and Ni were estimated in soil and plant samples Results The level of heavy metal was higher in soil than in plant parts studied. Accumulation of heavy metals varied from plant to plant. Pb was the highest in Calotropis procera root from HTA site and the lowest in Peristrophe bycaliculata whole plant from IA site. It was also lower in residential area than in heavy traffic area. Conclusion The level of heavy metal content differed in the same medicinal plant collected from environmentally different sites of the same city. Thus, it reiterates our belief that every medicinal plant sample should be tested for contaminant load before processing it further for medication.

关键词： Heavy metals Medicinal plants Lead Cadmium Chromium Herbal raw material

Influence of quenching medium on the dendrite morphology,hardness,and tribological behaviour of cast Cu-Ni-Sn spinodal alloy for defence application

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Defence Technology（防务技术） 2023年第12期30卷 83-100页

作者： Bipin Sankar Karthik V Shankar Vamu Sunil Hemanth Kashyap S Nikhil nair Adarsh A.nair Abhinav P M Department of Mechanical Engineering Amrita Vishwa VidyapeethamAmritapuriIndia

Cu-Ni-Sn spinodal alloys(Spinodal bronze)are potential materials with robust applications in components associated with defence applications like bearings,propellers,bushes,and shafts of heavily loaded aircraft,off-road vehicles,and *** paper presents a comparative study using water,Brine solution,and SAE 40 oil as the quenching media in regular bronze(Cu-6Sn)and spinodal bronze(Cu-9Ni-6Sn)*** analysis was conducted by optical microscopy,transmission electron microscopy(TEM),and X-ray diffraction technique(XRD)on bronze and spinodal bronze samples immersed in the three different quenching media to understand the grain size and hardness values *** analysis was performed to analyze the effect of quenching media on the wear aspects of bronze and spinodal bronze *** hardness value of the brine-aged spinodal bronze samples was as high as 320 Hv,and the grain size was very low in the range of 60μm.A quantitative comparison between brine-aged regular bronze and brine-aged spinodal bronze showed that the hardness(Hv)was almost 80%higher for brine-aged spinodal ***,the grain size was approximately 30%finer for spinodal bronze when compared with regular *** the load was increased in spinodal bronze samples,there was an initial dip in wear rate followed by a marginal *** was a steady increase in friction coefficient with a rise in load for brine-aged regular bronze and spinodal bronze *** results indicate that brine solution is the most effective quenching medium for cast Cu-Ni-Sn spinodal alloys.

关键词： Quenching Water Brine SAE 40 oil Grain size Hardness Wear rate Spinodal decomposition CuSn Spinodal alloy CuNiSn

Chemical and Microbial Characterization of Feed and Faeces of Two Giant Pill-Millipedes from Forests in the Western Ghats of India

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Pedosphere 2016年第6期26卷 861-871页

作者： Cheviri nair AMBARISH Kandikere Ramaiah SRIDHAR Department of Biochemistry St.Aloysius College Department of Biosciences Mangalore University

Soil macroinvertebrates are highly diverse and their major ecological service include breakdown of organic matter and in turn improve soil fertility and pill-millipedes are well-known for their significant role in ingestion, disintegration and decomposition of organic matter in soil. This study characterized the feed, the decomposing leaf litter of coconut （Cocos nucifera）, and faeces of two endemic giant pill-millipedes Arthrosphaera disticta and A. fumosa collected from forests of the Western Ghats of India based on chemical features and microbial profile. In both millipedes, electric conductivity and total phosphorus were significantly increased in faeces, while the crude protein, organic carbon, total nitrogen and total phenolics were significantly decreased, as compared to those in feed. Heterotrophic bacteria, actinomycetes, rhizobia and phosphate-solubilizing bacteria were significantly higher in faeces than in feed, while filamentous fungi and yeast substantially decreased in faces compared to feed in both the millipedes. Spectrum of fatty acid methyl esters was considerably different between feed and faeces of both the millipedes. The total saturated fatty acids were higher than the total unsaturated fatty acids in feed as well as faeces, while the ratio of unsaturated/saturated fatty acids decreased from feed to faeces. Dodecanoic and tetradecanoic acids in A. disticta and octadecanoic acid in A. fumosa significantly increased, while （9Z）-octadec-9-enoic and （9E,12E）-octadeca-9,12-dienoic acids in A.. disticta and hexadecanoic, tetracosanoic and （9E,12E）- octadeca-9,12-dienoic acids in A. fumosa significantly decreased in faeces compared to feed, indicating millipede-dependent changes in fatty acids. Icosanoic acid was present in faeces of both the millipedes, and hexadec-9-enoic acid was confined to faeces of A disticta, while pentadecanoic, heneicosanoic, （9Z,12Z,15Z）-9,12,15-octadecatrienoic and eicosenoic acids were confined to faeces of A. fumosa. Pil

关键词： Arthrosphaera coconut leaf litter fatty acids mesocosm microbiota nutrients