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Anisotropic turbulence of kinetic Alfvén waves and heating in solar corona

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Research in Astronomy and Astrophysics 2019年第12期19卷 327-342页

作者： Hemam dinesh singh Bheem singh Jatav Department of Physics Sikkim University

Understanding solar coronal heating has been one of the unresolved problems in solar physics in spite of the many theories that have been developed to explain it. Past observational studies suggested that kinetic Alfven waves(KAWs) may be responsible for solar coronal heating by accelerating the charged particles in solar plasma. In this paper, we investigated the transient dynamics of KAWs with modified background density due to ponderomotive force and Joule heating. A numerical simulation based on pseudospectral method was applied to study the evolution of KAW magnetic coherent structures and generation of magnetic turbulence. Using different initial conditions in simulations, the dependence of KAW dynamics on the nature of inhomogeneous solar plasma was thoroughly investigated. The saturated magnetic power spectra follow Kolmogorov scaling of k^-5/3 in the inertial range, then followed by steep anisotropic scaling in the dissipation range. The KAW has anisotropy of k||∝ k^0.53⊥, k|| ∝ k^0.50⊥, k||∝ k^0.83⊥ and k||∝ k^0.30⊥ depending on the kind of initial conditions of inhomogeneity. The power spectra of magnetic field fluctuations showing the spectral anisotropy in wavenumber space indicate that the nonlinear interactions may be redistributing the energy anisotropically among higher modes of the wavenumber. Therefore, anisotropic turbulence can be considered as one of the candidates responsible for the particle energization and heating of the solar plasmas.

关键词： plasmas turbulence waves Sun:corona

Coherent structures and spectral shapes of kinetic Alfvén wave turbulence in solar wind at 1 AU

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Research in Astronomy and Astrophysics 2019年第7期19卷 33-46页

作者： Hemam dinesh singh Bheem singh Jatav Department of Physics Sikkim University

This paper presents the generation of kinetic Alfv én wave(KAW) coherent structures of magnetic filaments applicable to solar wind at 1 AU,when the background plasma density is modified by parallel ponderomotive force and Joule *** inhomogeneity in the magnetic field,which was included as a perturbation in the transverse direction of the magnetic field,takes energy from the main pump KAWs and generates the filamentary *** the intensity is high enough,the filaments are broken down and the energy initially confined to low wavenumbers is redistributed to higher wavenumbers,leading to cascades of energy at small scales less than the ion acoustic gyroradius or comparable to electron *** magnetic field spectral profile is generated from the numerical simulation results,and its dependence on different directions of the wavevector and initial conditions of the simulation representing the transverse magnetic field inhomogeneity is *** relevance of these results with other spacecraft observations and measurements is also pointed out.

关键词： plasmas turbulence waves solar wind

Synthesis of Micron-sized Hexagonal and Flowerlike Nanostructures of Lead Oxide (PbO_2) by Anodic Oxidation of Lead

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Nano-Micro Letters 2011年第4期3卷 223-227页

作者： dinesh Pratap singh Onkar Nath Srivastava Estación Central Departamento de Física Department of Physics Banaras Hindu University

Micron sized hexagon- and flower-like nanostructures of lead oxide（α-PbO2） have been synthesized by very simple and cost effective route of anodic oxidation of lead sheet. These structures were easily obtained by the simple variation of applied voltage from 2-6 V between the electrodes. Lead sheet was used as an anode and platinum sheet served as a cathode. Anodic oxidation at 2 V resulted in the variable edge sized（1-2 μm） hexagon-like structures in the electrolyte. When the applied potential was increased to 4 V a structure of distorted hexagons consisting of some flower-like structures were obtained. Further increment of potential up to 6 V resulted in flower like structures of α-PbO2 having six petals. The diameter of the flower-like structures was 200-500 nm and the size of a petal was 100-200 nm.

关键词： Lead oxide nanostructures Anodic oxidation Hexagon-like structures Flower-like nanostructures

Effective parameter study for the facile and controlled growth of silver molybdate nano/micro rods

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Frontiers of Materials Science 2016年第4期10卷 375-384页

作者： Javier Esteban Enriquez MONTENEGRO dinesh Pratap singh Department of Physics University of Santiago Chile Avenida Ecuador 3493 Estacion Central Santiago 9170124 Chile

Controlled growth of nano/micro structures by controlling the effective parameters is the basic requirement for the application point of view in various areas. Here we report the facile growth of silver molybdate nanolmicro rods by mixing the solution of silver nitrate and ammonium molybdate at ambient condition followed by hydrothermal treatment at various temperatures for 12 h. To achieve the goal for the synthesis of long, high yield and homogeneous nanorods various effective parameters have been studied to set the most effective conditions for the growth. Among possible effective parameters first the temperature of the furnace was set by warring the temperature and then at the set temperature the concentration of reactants （NH4）6Mo7O24 and silver nitrate are varied respect to each other. The pH and temperature values were monitored during the mixing of the reactants. Structurallmicrostructural characterization revealed the optimum condition of 150℃ of the furnace and the concentration of （NH4）sMo7O24 and silver nitrate as described in various tables.

关键词： silver molybdate nanorod Ag6Mo10O33 controlled growth silver nitrate

Brain Tumor Segmentation through Level Based Learning Model

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Computer Systems Science & Engineering 2023年第1期44卷 709-720页

作者： K.dinesh Babu C.Senthil singh Department of Electronics and Communication Engineering Adhi College of Engineering and Technology631605India Department of Electronics and Communication Engineering Infant Jesus College of EngineeringVallanaduThoothukudi628851India

Brain tumors are potentially fatal presence of cancer cells over a human brain,and they need to be segmented for accurate and reliable planning of *** process must be carried out in different regions based on which the stages of cancer can be accurately *** patients exhibit a different level of challenge in terms of cancer or tumors detection as the Magnetic Resonance Imaging(MRI)images possess varying sizes,shapes,positions,and *** scanner used for sensing the location of tumors cells will be sub-jected to additional protocols and measures for accuracy,in turn,increasing the time and affecting the performance of the entire *** this view,Convolutional Neural Networks deliver suitable models for efficient segmentation and thus delivered promising *** previous strategies and models failed to adhere to diversity of sizes and shapes,proving to be a well-established solution for detecting tumors of bigger *** tend to be smaller in size and shape during their premature stages and they can easily evade the algorithms of Convolutional Neural Network(CNN).This proposal intends to furnish a detailed model for sensing early stages of cancer and hence perform segmentation irrespective of the current size and shape of *** size of networks and layers will lead to a significant weightage when multiple kernel sizes are involved,especially in multi-resolution *** the other hand,the proposed model is designed with a novel approach including a dilated convolution and level-based learning *** the convolution process is dilated,the process of feature extraction deals with multiscale objective and level-based learning eliminates the shortcoming of previous models,thereby enhancing the quality of smaller tumors cells and *** level-based learning approach also encapsulates the feature recon-struction processes which highlights the sensing of small-scale tumors ***,segmenting t

关键词： Glioma detection segmentation smaller tumour growth machine learning feature analysis

A Review on Pharmacological and Analytical Aspects of Naringenin

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Chinese Journal of Integrative Medicine 2018年第7期24卷 551-560页

作者： Kanika Patel Gireesh Kumar singh dinesh Kumar Patel G.L.A Institute of Pharmaceutical Research MathuraIndia Department of Pharmaceutics Institute of TechnologyBanaras Hindu UniversityVaranasi-221005India

Flavonoids are a widely distributed group of phytochemicals having benzo-pyrone nucleus, and more than 4,000 different flavonoids have been described and categorized into flavonols, flavones, flavanones, isoflavones, catechins and anthocyanidins. Flavonoids occurs naturally in fruits, vegetables, nuts, and beverages such as coffee, tea, and red wine, as well as in medical herbs. Flavonoids are responsible for the different colors of plant parts and are important constituents of the human diet. Flavanoids have different pharmacological activities, such as antioxidant, anti-allergic, antibacterial, anti-inflammatory, antimutagenic and anticancer activity. Naringenin belongs to the flavanones and is mainly found in fruits（grapefruit and oranges） and vegetables. Pharmacologically, it has anticancer, antimutagenic, anti-inflammatory, antioxidant, antiproliferative and antiatherogenic activities. Naringenin is used for the treatments of osteoporosis, cancer and cardiovascular diseases, and showed lipid-lowering and insulin-like properties. In the present review, detailed pharmacological and analytical aspects of naringenin have been presented, which revealed the impressive pharmacological profile and the possible usefulness in the treatment of different types of diseases in the future. The information provided in this communication will act as an important source for development of effective medicines for the treatment of various disorders.

关键词： analytical techniques flavonoids naringenin pharmacological activity phytoconstituents

Nanostructured porous polyaniline(PANI)coated carbon cloth(CC)as electrodes for flexible supercapacitor device

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Journal of Materials Science & Technology 2021年第29期88卷 168-182页

作者： dinesh J.Ahirrao Ajay Kumar Pal Vikalp singh Neetu Jha Department of Physics Institute of Chemical TechnologyMatunga(E)Mumbai400019India Department of Physics Ramniranjan Jhunjhunwala CollegeGhatkopar(W)Mumbai 400086India

Nanostructured porous polyaniline(PANI)has been synthesized and coated simultaneously on a highly flexible and conductive carbon cloth(CC)substrate using a simple in-situ chemical oxidative polymerization *** coated CC(PANI-CC)based flexible electrodes were further used for the fabrication of flexible supercapacitor *** the comparison purpose,pure PANI has also been synthesized and tested for its electrochemical *** energy storage capacity of PANI and PANI–CC composite was investigated using electrochemical techniques like CV,GCD,and EIS in a potential range from 0 to 0.8 V in 1 M H_(2)SO_(4)***-CC flexible electrodes exhibited the highest specific capacitance of 691 F/g;whereas,pure PANI could only achieve 575 F/g of specific capacitance at 1 A/*** also exhibited outstanding cyclic stability by recollecting 94%of its initial capacitance after 2000 GCD *** actual implementation,a flexible supercapacitor device has been fabricated using stainless steel sheets and PANI-CC flexile *** energy storage performance of the PANI-CC flexible supercapacitor device was tested at several bending angles,which resulted in 72%of capacitance retention at a maximum bending angle of 140°compared to the capacitance obtained at an angle 0°(flat state).PANI-CC exhibited improved electrochemical performance than pure PANI due to the synergistic effect between PANI and ***,CC helped in enhancing the conductivity and stability;whereas,PANI boosted the capacitance owing to its excellent porosity and fast pseudocapacitive charge storage response.

关键词： Polyaniline Carbon cloth Flexible supercapacitor Flexible electrode Composite

Does Glacial-Interglacial Transition Affect Sediment Accumulation in Monsoon-Dominated Regions?

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Acta Geologica Sinica(English Edition) 2017年第3期91卷 1079-1094页

作者： Dharmendra Pratap singh Rajeev SARASWAT dinesh K.NAIK Micropaleontology Laboratory Geological Oceanography DivisionNational Institute of Oceanography

The spatio-temporal changes in sedimentation rate along the continental margin of the monsoon-dominated eastern Arabian Sea during the last 24 kyr have been estimated from a compilation of 58 radiocarbon dated cores, in order to understand the effect of glacial-interglacial variation on sedimentation. The sedimentation rate has been computed for four-time slices, viz. the last glacial maximum, glacial-interglacial transition, early Holocene and late Holocene. We report that the average sedimentation rate in the slope to the abyssal region of the entire eastern Arabian Sea, although higher during the Holocene as compared with that during the last glacial maximum and glacial-interglacial transition, does not significantly vary during all four-time intervals. The sedimentation rate during any particular time interval, however, varies from core to core, thus indicating zonal changes. We report four zones of relatively high sedimentation rate, viz. the northeastern Arabian Sea, the region off the Gulf of Khambhat, the region off Goa and Mangalore, and off the southern tip of India. We suggest that a complex interaction of land-ocean-atmospheric processes controlled sedimentation rate in the eastern Arabian Sea during the last 24 kyr in such a way that the average sedimentation rate does not vary significantly, even during highly contrasting climatic conditions.

关键词： Sedimentation rate monsoon glacial Holocene Arabian Sea

Metallurgical Behaviour and Carbon Diffusion in Buttering Deposits Prepared With and Without Buffer Layers

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Acta Metallurgica Sinica(English Letters) 2017年第2期30卷 120-132页

作者： dinesh W.Rathod Sunil Pandey Sivanandam Aravindan Pavan Kumar singh Department of Mechanical Engineering Indian Institute of Technology Delhi Hauz-Khas New Delhi 110016 India School of MACE University of Manchester Manchester M13 9PL UK Bhabha Atomic Research Centre Mumbai 400085 India

Use of a buttering deposit on ferritic steel in dissimilar metal weld（DMW） joint is a common practice in nuclear plants to connect pressure vessel components（ferritic steel） to pipelines（austenitic stainless steel）.Carbon migration and metallurgical changes near fusion interface（ferritic steel–austenitic stainless steel） lead to a steeper gradient in material properties,and minimizing this gradient is the major challenge in the manufacturing of DMW *** 82 is often deposited on ferritic steel material as buttering to reducing the gradient of physical and attaining material *** 82/182 fillers are used to minimize the carbon migration,but the results are not truly *** this paper,Ni–Fe alloy（chromium-free） has been used as the intermediate buffer layer in the weld buttering deposit to address the issue of carbon migration and subsequent metallurgical *** weld pads with and without buffer layers of Ni–Fe alloy have been investigated and compared in detail for metallurgical properties and carbon ***–Fe buffer layer can significantly control the carbon migration which resists the metallurgical *** showed the better results in postweld heat treatment and thermally aged *** buttering deposit with Ni–Fe buffer layer could be the better choice for DMW joints requirements.

关键词： Dissimilar welds Buttering Carbon diffusion Buffer layer Metallurgical properties