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Effects of magnet Size and Geometry on magnetic Levitation Force

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Chinese Physics Letters 2007年第9期24卷 2664-2666页

作者： m. K. Alqadi H. m. Al-khateeb F. Y. Alzoubi N. Y. Ayoub Department of Physics Jordan University of Science and Technology Irbid Jordan School of Natural Applied Sciences German Jordanian University Amman Jordan

We obtain analytical relations for the levitation force as a function of dimensions of the superconductor-magnet system. The force has been calculated on the basis of the dipole-dipole interaction model. The effect of thickness of the superconductor on the levitation force is investigated. The results show that the influence of geometry and thickness of the magnet becomes significantly large at small levitation distances. Furthermore, approximating the permanent magnet as a point dipole results in an inaccurate estimation of the levitation force.

关键词： mEISSNER STATE

Formation of TiAlSi intermetallics during heating Ti-A356 Al mixed powder compact at semisolid temperature

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Journal of materials Science & Technology 2021年第35期94卷 247-263页

作者： m.Gao T.J.Chen Z.X.Zhang State Key Laboratory of Advanced Processing and Recycling of Nonferrous metals Lanzhou University of TechnologyLanzhou 730050China

Due to the similarity in composition and crystal structure of some Ti Al Si ternary intermetallics,it is quite difficult to accurately confirm their physic characteristics,and thus,to tailor microstructure to improve mechanical properties of metal materials related to the Ti Al Si ***,the formation process of Ti Al Si intermetallics was investigated during heating Ti-A356 mixed powder compact at a A356 alloy semisolid temperature of 595℃.The results indicated that two kinds of intermetallics ofτ1(tetragonal,I41/amd)andτ2(orthorhombic,Cmcm)generated,and both the concentration and supply direction of Ti atoms,which are related to local breakage of oxide films on neighboring Ti and A356 alloy powders,determined the phase and morphology of the intermetallics.τ1 andτ2 crystals all had an intrinsic plate morphology,butτ2 crystals were thinner due to more anisotropic growth resulted from their high density of stacking faults(SFs).τ1 lamellar domains generated during growth ofτ2 crystals,which were accompanied by decrease in density of *** combined effect of size difference and internal energy difference betweenτ1 andτ2 crystals made largeτ1 crystals coarsen at the expense ofτ2 crystals in Ostwald ripening,leading them to finally evolve into an agglomerate of largeτ1 plates.

关键词： Intermetallics Stacking faults Growth Phase transformation

Reduced tillage with residue retention improves soil labile carbon pools and carbon lability and management indices in a seven-year trial with wheat-mung bean-rice rotation

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Pedosphere 2022年第6期32卷 916-927页

作者： Rafeza BEGUm mohammad m.R.JAHANGIR mohammad JAHIRUDDIN mohammad Rafiqul ISLAm Shaikh m.BOKHTIAR Khandakar R.ISLAm Department of Soil Science Bangladesh Agricultural UniversityMymensingh 2202(Bangladesh) Soil Resource Development Institute Dhaka 1215(Bangladesh) South Asian Association for Regional Cooperation(SAARC)Agriculture Center Dhaka 1215(Bangladesh) The Ohio State University Columbus OH 43235(USA)

Soil total organic carbon(TOC)is a composite indicator of soil quality with implications for crop production and the regulation of soil ecosystem *** reports on the dynamics of TOC as a consequence of soil management practices in subtropical climatic conditions,where microbial carbon(C)loss is high,are very *** objective of our study was to evaluate the impact of seven years of continuous tillage and residue management on soil TOC dynamics(quantitative and qualitative)with respect to lability and stratification under an annual wheat-mung bean-rice cropping *** soil samples were collected at 0-15 and 15-30 cm depths from a three-replicate split-plot experiment with tillage treatment as the main plots and crop residue levels as the *** tillage treatments included conventional tillage(CT)and strip tillage(ST).Residue levels were high residue level(HR),30%of the plant height,and low residue level(LR),15%.In addition to TOC,soil samples were analyzed for particulate organic C(POC),permanganate oxidizable C(POXC),basal respiration(BR),specific maintenance respiration rate(qCO_(2)),microbial biomass C(mBC),potentially mineralizable C(PmC),and TOC lability and management *** ST treatment significantly increased the TOC and labile C pools at both depths compared with the CT treatment,with the effect being more pronounced in the surface *** HR treatment increased TOC and labile C pools compared with the LR *** ST+HR treatment showed significant increases in mBC,metabolic quotient(qR),C pool index(CPI),C lability index(CL_(I)),and C management index(CmI),indicating improved and efficient soil biological activities in such systems compared with the CT ***,the stratification values,a measure of soil quality improvement,for POC and mBC were>2,indicating improved soil quality in the ST+HR treatment compared with the CT *** ST+HR treatment not only significantly increased the contents o

关键词： basal respiration carbon management index carbon stratification particulate organic carbon permanganate oxidizable carbon total organic carbon

Estimation of Hourly and Daily Global Solar Radiation at Clear Days Using an Approach Based on modified Version of Gaussian Distribution

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Advances in Atmospheric Sciences 1996年第3期13卷 349-358页

作者： S.m EI shazly Department of Physics.Faculty of Science South Valley UniversityQenaA.R.Egypt

The performance of two models,Jam and Baig,based on the modified version of Gaussian distribution function in estimating the daily total of global solar radiation and its distribution through the hours of the day from sunrise to sunset al any clear day is evaluated with our own measured data in the period from June 1992 to may 1993 in Qena Egypt The results show a high relative deviation of calculated values from measured ones,especially for Jain model,in the most hours of the day,except for those near to local *** misfit behavior is quite obvious in the early morning and late afternoon A new approach has been proposed in this paper to estimate the daily and hourly global solar radiation This model performs with very high accuracy on the recorded data in our *** validity of this approach was verified with new measurements in some clear days in June and August *** resultant very low relative deviation of the calculated values of global solar radiation from the measured ones confirms the high performance of the approach proposed in this work

关键词： Glohal solar radiation,. measurements models Gaussian distribution function Statistical treatment

Viability of recalcitrant Araucaria angustifolia seeds in storage and in a soil seed bank

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Journal of Forestry Research 2020年第6期31卷 2413-2422页

作者： Ezequiel Gasparin Jose m.R.Faria Anderson CJose Olivia AOTonetti Rodrigo Ade melo Henk W.m.Hilhorst Departamento de Ciencias Florestais Universidade Federal de Santa Maria(UFSM)Avenida Roraima1000CamobiSanta MariaRS 97105-900Brazil Departamento de Ciencias Florestais Universidade Federal de Lavras(UFLA)Caixa Postal 3017LavrasMGBrazi1 Wageningen Seed Lab Laboratory of Plant PhysiologyWageningen UniversityDroevendaalsesteeg 16708 PB WageningenThe Netherlands

Araucaria angustifolia(Bertol.)Kuntze is a representative species of the mixed Ombrophilous Forest in the Atlantic Forest Biome of *** development of a germplasm conservation protocol for long-term seed bank storage is compromised for this species,as it is sensitive to ***,in situ establishment of a soil seed bank in its natural habitat may be *** study evaluates the storability of two provenances of *** seeds and their behavior in an artificial soil seed bank in two forest environments(understory and edge).Results show that both seed provenances may be stored at 5C for approximately 12 months,retaining high *** subsequent decrease in germination was associated with a reduction and an increase in seed water content,as well as with increased electrical *** the understory environment,seed viability was above 85%for the first 60 days,and at the end of the experiment(270 days),seedlings ***,at the forest edge,there was a total loss of seed viability after 120 days associated with a reduction in water content and high *** is concluded,therefore,that short-term storage of *** seeds is possible in a cold room,which is fundamental to supply seed demand outside the production *** cover conservation is important for regeneration and conservation of the species.

关键词： Brazilian pine Desiccation sensitivity Forest cover Soil seed bank Storability

A generic and extensible model for the martensite start temperature incorporating thermodynamic data mining and deep learning framework

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Journal of materials Science & Technology 2022年第33期128卷 31-43页

作者： Chenchong Wang Kaiyu Zhu Peter Hedström Yong Li Wei Xu State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China Department of materials Science and Engineering KTH Royal Institute of TechnologyStockholm 10044Sweden

The martensite start temperature is a critical parameter for steels with metastable *** numerous models have been developed to predict the martensite start(ms)temperature,the complexity of the martensitic transformation greatly limits their performance and *** this work,we apply deep data mining of thermodynamic calculations and deep learning to develop a generic model for *** data mining was used to establish a hierarchical database with three levels of ***,a convolutional neural network model,which can accurately treat the hierarchical data structure,was used to obtain the final *** integrating thermodynamic calculations,traditional machine learning and deep learning modeling,the final predictor model shows excellent generalizability and extensibility,*** performance both within and beyond the composition range of the original *** effects of 15 alloying elements were considered successfully using the proposed *** work suggests that,with the help of deep data mining considering the physical mechanisms,deep learning methods can partially mitigate the challenge with limited data in materials science and provide a means for solving complex problems with small databases.

关键词： martensite transformation Data mining Deep learning Extensibility Small-sample problem

Vibrations in magnet/Superconductor Levitation Systems

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Chinese Physics Letters 2006年第6期23卷 1641-1644页

作者： F. Y. Alzoubi H. m. Al-khateeb m. K. Alqadi N. Y. Ayoub Department of Physics Jordan University of Science and Technology Irbid Jordan Department of Physics Yarmouk University Irbid Jordan School of Applied Natural Sciences German Jordanian University Amman Jordan

The problem of a small magnet levitating above a very thin superconducting disc in the meissner state is analysed. The dipole-dipole interaction model is employed to derive analytical expressions for the interaction energy, levitation force, magnetic stiffness and frequency of small vibrations about the equilibrium position in two different configurations, i.e. with the magnetic moment parallel and perpendicular to the superconductor. The results show that the frequency of small vibrations decreases with the increasing levitation height for a particular radius of the superconducting disc, which is in good agreement with the experimental results. However, the frequency increases monotonically up to saturation by increasing the radius of the disc for a particular height of the magnet. In addition, the frequency of vibrations is higher when the system is in the vertical configuration than that when the system is in the horizontal configuration.

关键词： mEISSNER STATE SmALL mAGNET FORCE STIFFNESS SUPERCONDUCTORS SIZE

Raman spectroscopy of isolated carbyne chains confined in carbon nanotubes:Progress and prospects

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Chinese Physics B 2022年第12期31卷 532-542页

作者： Johannes m.A.Lechner Pablo Hernández López Sebastian Heeg Institut fur Physik and IRIS Adlershof Humboldt Universitat zu Berlin12489 BerlinGermany

Carbyne is an infinitely long linear chain of carbon atoms with sp1hybridization and the truly one-dimensional allotrope of *** obtaining freestanding carbyne is still an open challenge,the study of confined carbyne,linear chains of carbon encapsulated in carbon nanotubes,provides a pathway to explore carbyne and its remarkable properties in a well-defined *** this review,we discuss the basics and recent advances in studying single confined carbyne chains by Raman spectroscopy,which is their primary spectroscopic characterization *** highlight where single carbyne chain studies are needed to advance our understanding of confined carbyne as a material system and provide an overview of the open questions that need to be addressed and of those aspects currently under debate.

关键词： carbyne linear carbon chains carbon nanotubes Raman spectroscopy

Deep Imitation Learning for Autonomous Vehicles Based on Convolutional Neural Networks

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IEEE/CAA Journal of Automatica Sinica 2020年第1期7卷 82-95页

作者： Parham m.Kebria Abbas Khosravi Syed moshfeq Salaken Saeid Nahavandi Intelligent Systems Research and Innovation(IISRI) Deakin UniversityWaurn PondsVIC 3216Australia

Providing autonomous systems with an effective quantity and quality of information from a desired task is challenging. In particular, autonomous vehicles, must have a reliable vision of their workspace to robustly accomplish driving functions. Speaking of machine vision, deep learning techniques, and specifically convolutional neural networks, have been proven to be the state of the art technology in the field. As these networks typically involve millions of parameters and elements, designing an optimal architecture for deep learning structures is a difficult task which is globally under investigation by researchers. This study experimentally evaluates the impact of three major architectural properties of convolutional networks, including the number of layers, filters, and filter size on their performance. In this study, several models with different properties are developed,equally trained, and then applied to an autonomous car in a realistic simulation environment. A new ensemble approach is also proposed to calculate and update weights for the models regarding their mean squared error values. Based on design properties,performance results are reported and compared for further investigations. Surprisingly, the number of filters itself does not largely affect the performance efficiency. As a result, proper allocation of filters with different kernel sizes through the layers introduces a considerable improvement in the *** of this study will provide the researchers with a clear clue and direction in designing optimal network architectures for deep learning purposes.

关键词： Autonomous vehicles convolutional neural networks deep learning imitation learning