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Characteristics and Temperature measurement of a Non-Transferred Cascaded DC Plasma Torch

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Plasma Science and Technology 2010年第2期12卷 181-187页

作者： B.BORA N.AOmOA m.KAKATI Thermal Plasma Processed materials Laboratory Centre of Plasma Physics Institute for Plasma Research Department of Physics Dibrugarh University

Dependence of the current-voltage characteristics of a non-transferred DC cascaded plasma torch used for nanoparticle synthesis, on the plasma current and the plasma argon gas flow rate are reported in this paper. The potential structure inside the torch and its dependence on the plasma current and gas flow rate are also investigated. The arc voltage is seen to exhibit negative characteristic for a current below 150 A and positive characteristic above that current value. The voltage drop near the electrodes is found to decrease with the increase in plasma current. 25~ of the total voltage is dropped near the cathode at a plasma current of 50 A and a argon plasma gas flow rate of 10 liter per minute （LPm）, and it decreases to 12% with the current increasing to 300 A, and to 17% with a gas flow rate of 25 LPm. The variation in the torch efficiency with the gas flow rate and plasma current is also reported. The efficiency of the torch is found to be between 36% and 48%. In addition, the plasma gas temperature at various positions of the reactor and for different currents and voltages are measured by calorimetric estimation with a heat balance technique.

关键词： DC plasma torch current voltage characteristics thermal efficiency temper- ature measurements

Nonlocal buckling of embedded magnetoelectroelastic sandwich nanoplate using refined zigzag theory

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Applied mathematics and mechanics(English Edition) 2018年第4期39卷 529-546页

作者： A.GHORBANPOUR-ARANI F.KOLAHDOUZAN m.ABDOLLAHIAN Faculty of mechanical Engineering University of Kashan Institute of Nanoscience & Nanotechnology University of Kashan

This paper is concerned with a buckling analysis of an embedded nanoplate integrated with magnetoelectroelastic(mEE) layers based on a nonlocal magnetoelectroelasticity theory. A surrounding elastic medium is simulated by the Pasternak foundation that considers both shear and normal loads. The sandwich nanoplate(SNP) consists of a core that is made of metal and two mEE layers on the upper and lower surfaces of the core made of Ba Ti O3/Co Fe2 O4. The refined zigzag theory(RZT) is used to model the SNP subject to both external electric and magnetic potentials. Using an energy method and Hamilton’s principle, the governing motion equations are obtained, and then solved analytically. A detailed parametric study is conducted, concentrating on the combined effects of the small scale parameter, external electric and magnetic loads, thicknesses of mEE layers, mode numbers, and surrounding elastic medium. It is concluded that increasing the small scale parameter decreases the critical buckling loads.

关键词： sandwich nanoplate(SNP) refined zigzag theory(RZT) nonlocal magnetoelectroelasticity theory buckling magnetostrictive layer

Effects of Carbon Fiber Gas Pressure,Temperature and Deposition Distance on Thermo Fluids Phenomena in Vacuum Deposition machine

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Journal of Thermal Science 2008年第3期17卷 253-260页

作者： Ying HE m.Ota S.K.Stefanov Dept. mech. Eng. Tokyo Metropolitan University 1-1 Minami-Osawa Hachioji-shi Tokyo 192-0397 Japan Institute of mechanics BASci. Acad. G Bonchev Str. B1.4 Sofia 1113 Bulgaria

A numerical analysis method （DSmC, Direct Simulation monte Carlo）[1] was developed to simulate the molecular motion of rarefied gases. In the present paper, numerical approaches by the DSmC method have been carded out. By the computation model of CC-40F carbon coater, the cylindrical deposition machine has axial symmetry; the flows inside the vacuum chamber were analyzed. The substrates were put on the bottom and the fiber near the ceiling in the computational domain. In the computational model, air and carbon molecules are working ones. The effects of the air gas pressure variation in the chamber, the effects of the deposition distance variation and the surface temperature variation of the carbon fiber on thermo fluids phenomena are discussed and visualized. Changing the number density of carbon and air, the temperature of the carbon and the velocity of the carbon in the chamber are discussed. With changing the surface temperature of the carbon fiber, qualitative assay of experiment and simulation result is in similar trend very well. The DSmC method is a forceful tool for the study of rarefied gas flow in vacuum deposition machine.

关键词： Rarefied gas flow Knudsen number DSmC method vacuum carbon deposition mEmS

Fabrication of plain carbon steel/high chromium white cast iron bimetal by a liquid–solid composite casting process

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International Journal of minerals,metallurgy and materials 2015年第9期22卷 950-955页

作者： V.Javaheri H.Rastegari m.Naseri Division of Research and Development Isfahan Casting Industries Co.(ICI) Department of Engineering Birjand University of Technology

High-chromium white cast iron （HCWCI） is one of the most widely used engineering materials in the mining and cement industries. However, in some components, such as the pulverizer plates of ash mills, the poor machinability of HCWCI creates difficulties. The bimetal casting technique is a suitable method for improving the machinability of HCWCI by joining an easily machined layer of plain carbon steel （PCS） to its hard part. In this study, the possibility of PCS/HCWCI bimetal casting was investigated using sand casting. The investigation was conducted by optical and electron microscopy and non-destructive, impact toughness, and tensile tests. The hardness and chemical composition profiles on both sides of the interface were plotted in this study. The results indicated that a conventional and low-cost casting technique could be a reliable method for producing PCSYdCWCI bimetal. The interfacial microstructure comprised two distinct lay- ers： a very fine, partially spheroidized pearlite layer and a coarse full pearlite layer. moreover, characterization of the microstructure revealed that the interface was free of defects.

关键词： bimetals carbon steel cast iron casting interfaces microstructure mechanical properties

Framework for COVID-19 Segmentation and Classification Based on Deep Learning of Computed Tomography Lung Images

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Journal of Electronic Science and Technology 2022年第3期20卷 246-256页

作者： Wessam m.Salama moustafa H.Aly the Department of Basic Science Faculty of EngineeringPharos UniversityAlexandria12455Egypt the Department of Electronics and Communications Engineering College of Engineering and TechnologyArab Academy for ScienceTechnology and Maritime TransportAlexandria1029Egypt

Corona Virus Disease 2019(COVID-19) has affected millions of people worldwide and caused more than6.3 million deaths(World Health Organization, June 2022). Increased attempts have been made to develop deep learning methods to diagnose COVID-19 based on computed tomography(CT) lung images. It is a challenge to reproduce and obtain the CT lung data, because it is not publicly available. This paper introduces a new generalized framework to segment and classify CT images and determine whether a patient is tested positive or negative for COVID-19 based on lung CT images. In this work, many different strategies are explored for the classification ***50 and VGG16 models are applied to classify CT lung images into COVID-19 positive or negative. Also,VGG16 and ReNet50 combined with U-Net, which is one of the most used architectures in deep learning for image segmentation, are employed to segment CT lung images before the classifying process to increase system performance. moreover, the image size dependent normalization technique(ISDNT) and Wiener filter are utilized as the preprocessing techniques to enhance images and noise suppression. Additionally, transfer learning and data augmentation techniques are performed to solve the problem of COVID-19 CT lung images deficiency, therefore the over-fitting of deep models can be avoided. The proposed frameworks, which comprised of end-to-end, VGG16,ResNet50, and U-Net with VGG16 or ResNet50, are applied on the dataset that is sourced from COVID-19 lung CT images in Kaggle. The classification results show that using the preprocessed CT lung images as the input for U-Net hybrid with ResNet50 achieves the best performance. The proposed classification model achieves the 98.98%accuracy(ACC), 98.87% area under the ROC curve(AUC), 98.89% sensitivity(Se), 97.99 % precision(Pr), 97.88%F-score, and 1.8974-seconds computational time.

关键词： Augmentation classification computed tomography(CT) Corona Virus Disease 2019(COVID-19) deep learning ResNet50 segmentation U-Net VGG16

Geochemistry of metasedimentary rocks of the Sonakhan and mahakoshal greenstone belts,Central India:Implications for paleoweathering,paleogeography and mechanisms of greenstone belt development

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Acta Geochimica 2022年第1期41卷 64-83页

作者： Hamidullah Wani m.E.A.mondal Iftikhar Ahmad Department of Geology Government Degree College for Women PulwamaJammu and Kashmir 192301India Department of Geology Aligarh Muslim UniversityAligarhUttar Pradesh 202002India

A comparative study of the Precambrian Sonakhan(SGB)and mahakoshal(mGB)greenstones belts of Central India has been undertaken to decipher their provenance,paleoweathering,paleogeography,and *** compared to the Upper Continental Crust(UCC),the mGB samples are enriched while the SGB samples are depleted in mafic elements indicating the presence of mafic rocks in the source of the *** is complemented by the Ni–Cr *** REE concentrations,LREE fractionated patterns and negative Eu anomalies of the mGB and SGB samples indicate derivation of sediments from a highly fractionated granitic *** mGB samples also contain the geochemical signature of mafic rocks,it is,therefore proposed that the mGB clastic load were derived from two sources(mafic+felsic)with arc *** is attested by Cr and Zr relationships,and LILE enrichment,and HFSE *** features suggest that the SGB developed as autochthonous while the mGB developed as an allochthonous *** chemical alteration indices such as chemical index of alteration(CIA),plagioclase index of alteration(PIA),and index of compositional variability for mGB samples indicate that they were dominantly derived as the first cycle(with minor recycled)sediments from bimodal sources(dominantly continental arcs)by intense chemical weathering as compared to the SGB samples,which were derived from felsic sources(dominantly cratonic rocks),and partly by recycling through a low chemical *** CIA and PIA values of the samples reveal a change in the climatic conditions from Late Archean to Late *** change is interpreted in terms of migration of the Indian plate from high latitudes in the Late Archean to lower latitudes during the Late *** is consistent with the paleomagnetic data that placed India in the configuration of 2.45 Ga Ur and 1.78 Ga Columbia supercontinents.

关键词： Central Indian Shield Sonakhan and mahakoshal greenstone belts Paleoweathering and paleogeography Greenstone belt development

The effect of Fe doping on structural and magnetic properties of nanocrystallite Co_2Cr_(1-x)Fe_xAl Heusler alloys prepared by mechanical alloying

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Chinese Physics B 2012年第11期21卷 459-466页

作者： m.Hakimi P.Kameli H.Salamati Department of Physics Isfahan University of Technology

mechanical alloying has been used to produce nanocrystallite Co2Crl-xFexAl （x = 0, 0.4, 0.6, 1） Heusler alloys. The formation of the L21 phase of Co2Cr1-xFexAl by the mechanical alloying method was investigated. The effect of Fe doping on the structural and magnetic properties of the samples was also studied. The results were compared with the Slater Pauling prediction. A comparison between these samples and those prepared by the arc-melting method in the literature was made. An increase of the coercivity Hc with the increasing Fe doping level was observed. This phenomenon was explained by the increases of lattice strain and magnetic anisotropy with the increasing Fe content.

关键词： magnetic property X-ray diffraction nanocrystallite mechanical property

Surface plasmon polariton at the interface of dielectric and graphene medium using Kerr effect

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Chinese Physics B 2018年第11期27卷 522-527页

作者： Bakhtawar muhammad Haneef B A Bacha H Khan m Atif Lab of Theoretical Physics Department of Physics Hazara University Department of Physics University of Malakand

We theoretically investigate the control of surface plasmon polariton（SPP） generated at the interface of dielectric and graphene medium under Kerr nonlinearity. The controlled Kerr nonlinear signal of probe light beam in a dielectric medium is used to generate SPPs at the interface of dielectric and graphene medium. The positive, negative absorption, and dispersion properties of SPPs are modified and controlled by the control and Kerr fields. A large amplification（negative absorption） is noted for SPPs under the Kerr nonlinearity. The normal/anomalous slope of dispersion and propagation length of SPPs is modified and controlled with Kerr nonlinearity. This leads to significant variation in slow and fast SPP propagation. The controlled slow and fast SPP propagation may predict significant applications in nano-photonics, optical tweezers, photovoltaic devices, plasmonster, and sensing technology.

关键词： surface plasmon polariton Kerr nonlinearity graphene

The Response of the Earth's Lower Ionosphere to Gamma-Ray Solar Flares and their Associated X-ray

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Research in Astronomy and Astrophysics 2022年第4期22卷 137-152页

作者： mahmoud mohery Hussein m.Farid Alaa Ali Dept.of Phys College of ScienceUniversity of JeddahJeddahSaudi Arabia Astronomy Space Science&Meteorology DepartmentFaculty of ScienceCairo UniversityGiza 12613Egypt Astronomy Dept. Faculty of ScienceKing Abdulaziz University21589 JeddahSaudi Arabia

The present work aims to explore the impact of solar gamma-ray fiares(GRFs),detected by the Fermi-Large Area Telescope(LAT),and their associated X-ray fiares(XRFs)on the Earth’s lower *** data of ionospheric parameter fmin were collected from the Yamagawa mid-latitude ionosonde station in *** most of the GRFs used in this study are associated with soft X-ray(SXR)emissions,detected by the Geostationary Operational Environmental Satellite(GOES),we classified them into three types:simultaneous(S),delayed(D)and not associated(N),refiecting the phase occurrence of the solar ***,the ionospheric D layer responds strongly to XRFs more than *** temporal profiles of the ionospheric parameter fmin show distinct behaviors as a response to the various GRF *** the case of the S-type,a single strong peak,with an average value of 5.2 mHz,emanates in the fmin profile within an average interval of time of less than half an *** the case of the D-type,two successive peaks appear in the fmin profile,with an average value of 6.0 mHz for the second peak through a time interval of one hour after the onset of gamma-ray(GR)*** response of the fmin parameter to the N-type fiares appears as a single peak with an average value of 4.8 mHz within about an *** notice that the difference between the fmin peak values and the corresponding reference ones(dfmin)is more convenient and representative than the fmin values,where the median GR fiux of the S-,D-and N-types tends to increase as the average dfmin increases.

关键词： Sun:X-rays gamma-rays Earth:ionosphere satellites