Li, Jing

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Now showing 1 - 10 of 11
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    ML@GT Lab presents LAB LIGHTNING TALKS 2020
    ( 2020-12-04) AlRegib, Ghassan ; Chau, Duen Horng ; Chava, Sudheer ; Cohen, Morris B. ; Davenport, Mark A. ; Desai, Deven ; Dovrolis, Constantine ; Essa, Irfan ; Gupta, Swati ; Huo, Xiaoming ; Kira, Zsolt ; Li, Jing ; Maguluri, Siva Theja ; Pananjady, Ashwin ; Prakash, B. Aditya ; Riedl, Mark O. ; Romberg, Justin ; Xie, Yao ; Zhang, Xiuwei
    Labs affiliated with the Machine Learning Center at Georgia Tech (ML@GT) will have the opportunity to share their research interests, work, and unique aspects of their lab in three minutes or less to interested graduate students, Georgia Tech faculty, and members of the public. Participating labs include: Yao’s Group - Yao Xie, H. Milton Stewart School of Industrial Systems and Engineering (ISyE); Huo Lab - Xiaoming Huo, ISyE; LF Radio Lab – Morris Cohen, School of Electrical Computing and Engineering (ECE); Polo Club of Data Science – Polo Chau, CSE; Network Science – Constantine Dovrolis, School of Computer Science; CLAWS – Srijan Kumar, CSE; Control, Optimization, Algorithms, and Randomness (COAR) Lab – Siva Theja Maguluri, ISyE; Entertainment Intelligence Lab and Human Centered AI Lab – Mark Riedl, IC; Social and Language Technologies (SALT) Lab – Diyi Yang, IC; FATHOM Research Group – Swati Gupta, ISyE; Zhang's CompBio Lab – Xiuwei Zhang, CSE; Statistical Machine Learning - Ashwin Pananjady, ISyE and ECE; AdityaLab - B. Aditya Prakash, CSE; OLIVES - Ghassan AlRegib, ECE; Robotics Perception and Learning (RIPL) – Zsolt Kira, IC; Eye-Team - Irfan Essa, IC; and Mark Davenport, ECE.
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    Numerical Modeling on Reciprocating Active Magnetic Refrigeration Regenerator at Room Temperature
    (Georgia Institute of Technology, 2008-05) Li, Jing ; Numazawa, T. ; Matsumoto, K. ; Nakagome, H.
    A 2-dimension porous media model has been constructed for Reciprocating Active Magnetic Refrigeration Regenerator (AMR). The 2-D model is solved using a fully implicit (in time and space) discretization of the 2-dimension Navier-Stocks equations and governing energy equation. The magneto-caloric effect (MCE) is taken into account by the inclusion of a source term in the energy equation for the magnetic solid. The solid magnetic material and the regeneration fluid are separately modeled. The adiabatic temperature change of the gadolinium is used for mean field modeling. Typical results are presented based on the condition of experimental AMR.
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    Interphase exchange coupling in Fe/Sm–Co bilayers with gradient Fe thickness
    (Georgia Institute of Technology, 2005-09-30) Yu, Ming-hui ; Hattrick-Simpers, Jason ; Takeuchi, Ichiro ; Li, Jing ; Wang, Z. L. (Zhong Lin) ; Liu, J. Ping ; Lofland, S. E. ; Tyagi, Somdev ; Freeland, J. W. ; Giubertoni, D. ; Bersani, M. ; Anderle, M.
    We have fabricated Fe/Sm–Co bilayers with gradient Fe thicknesses in order to systematically study the dependence of exchange coupling on the thickness of the Fe layer. The Fe layer was deposited at two different temperatures (150 and 300 °C) to study the effect of deposition temperature on the exchange coupling. Magneto-optical Kerr effect and x-ray magnetic circular dichroism (XMCD) have been employed as nondestructive rapid characterization tools to map the magnetic properties of the gradient samples. Systematic enhancement in exchange coupling between the soft layer and the hard layer is observed as the soft layer thickness is decreased. Separate exchange couplings of the Fe layer with Co and Sm in the hard layer are revealed through measuring the element-specific hysteresis curves using XMCD. The single-phase-like magnetization reversal critical thickness increases from 12 nm for Fe deposited at 150 °C to 24 nm for Fe deposited at 300 °C, indicating an important role of the state of the interface in the exchange coupling.
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    Grain size dependence of magnetic properties in shock synthesized bulk Pr₂Fe₁₄B/α-Fe nanocomposites
    (Georgia Institute of Technology, 2004-09-15) Jin, Z. Q. ; Thadhani, Naresh N. ; McGill, M. ; Li, Jing ; Ding, Yong ; Wang, Z. L. (Zhong Lin) ; Zeng, Hao ; Chen, M. ; Cheng, S.-F. ; Liu, J. Ping
    The structural and magnetic properties of the melt-spun Pr₂Fe₁₄B/α-Fe nanocomposite powders consolidated via shock-wave compression and subjected to postshock thermal treatment were investigated. Shock compression results in grain refinement, which leads to a reduction of an effective anisotropy and therefore an increase in the ferromagnetic exchange length, resulting in an enhanced exchange coupling in fully consolidated bulk magnets. A small amount of amorphous phase formed during the shock compression were observed to crystallize into Pr₂Fe₁₄B upon annealing above 600 °C. The heat treatment also results in the recovery of coercivity partially lost during the consolidation, which can be related directly to the dependence of the effective anisotropy on the grain size, as illustrated by the transmission electron microscopy observation of grain refinement in the shock-consolidated bulk samples. A uniform grain morphology is suggested as a means for further increasing the magnetic properties of bulk nanocomposites.
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    Tailoring magnetic properties of core/shell nanoparticles
    (Georgia Institute of Technology, 2004-08-02) Zeng, Hao ; Sun, Shouheng ; Li, Jing ; Liu, J. Ping ; Wang, Z. L. (Zhong Lin)
    Bimagnetic FePt/MFe₂O₄ sM=Fe,Cod core/shell nanoparticles are synthesized via high-temperature solution phase coating of 3.5 nm FePt core with MFe₂O₄ shell. The thickness of the shell is controlled from 0.5 to 3 nm. An assembly of the core/shell nanoparticles shows a smooth magnetization transition under an external field, indicating effective exchange coupling between the FePt core and the oxide shell. The coercivity of the FePt/Fe₃O₄ particles depends on the volume ratio of the hard and soft phases, consistent with previous theoretical predictions. These bimagnetic core/shell nanoparticles represent a class of nanostructured magnetic materials with their properties tunable by varying the chemical composition and thickness of the coating materials.
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    Bulk nanocomposite magnets produced by dynamic shock compaction
    (Georgia Institute of Technology, 2004-07-15) Chen, K. H. ; Jin, Z. Q. ; Li, Jing ; Kennedy, G. ; Wang, Z. L. (Zhong Lin) ; Thadhani, Naresh N. ; Zeng, Hao ; Cheng, S.-F. ; Liu, J. Ping
    Exchange-coupled R₂Fe₁₄B/α -Fe (R = Nd or Pr) nanocomposite bulk magnets with nearly full density have been successfully produced by shock compaction of melt-spun powders. X-ray diffraction and transmission electronic microscopy analyses of the shock-consolidated compacts showed no grain growth upon compaction, in fact, a decrease in the crystallite size of both the hard and soft phases was observed. As a consequence, magnetic properties were retained and even improved after compaction. Hysteresis loops of the shock-consolidated powder compacts showed a smooth single-phaselike behavior, indicating effective exchange coupling between hard and soft magnetic phases.
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    Interface structures in FePt/Fe₃Pt hard-soft exchange-coupled magnetic nanocomposites
    (Georgia Institute of Technology, 2003-05-26) Li, Jing ; Wang, Z. L. (Zhong Lin) ; Zeng, Hao ; Sun, Shouheng ; Liu, J. Ping
    Self-assembly of FePt and Fe₃O₄ nanoparticles of different sizes led to various FePt–Fe₃O₄ nanocomposites. Annealing the composite under reducing atmosphere at 650 and 700 °C induced magnetically hard FePt phase and magnetically soft Fe₃Pt phase. The FePt and Fe₃Pt phases were either linked by a common interface or coexisted within one grain as domains with sizes <10 nm. This ensures the effective exchange coupling of magnetically hard and soft phases. High-resolution transmission electron microscopy studies provide detailed structural characterization for the FePt based nanocomposites.
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    Synthesis, chemical ordering, and magnetic properties of FePtCu nanoparticle films
    (Georgia Institute of Technology, 2003-05-15) Sun, Xiangcheng ; Kang, Shishou ; Harrell, J. W. ; Nikles, David E. ; Dai, Z. R. ; Li, Jing ; Wang, Z. L. (Zhong Lin)
    FePtCu nanoparticles with varying composition were prepared by the simultaneous polyol reduction of platinum acetylacetonate and copper bis(2,2,6,6-tetramethyl-3,5-heptanedionate) and the thermal decomposition of iron pentacarbonyl. As prepared the particles had a fcc structure with an average diameter of 3.5 nm and were superparamagnetic. Heat treatment of the self-assembled films at temperatures above 550 °C transformed the particles from the fcc to the L1₀ phase, give in-plane coercivities as high as 9000 Oe. X-ray diffraction revealed that the Cu remained in the films and the presence of an extra peak, indicating a second phase was present. Consistent with two or more phases, the magnetic hysteresis curves could be decomposed into a hard component (H[subscript c]c>5000 Oe) and a soft component (H[subscript c]c<2000 Oe). Unlike our earlier results for Ag in FePt, adding Cu to FePt did not lower the temperature required for phase transformation from the fcc to the L1₀ phase.
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    Interparticle interactions in annealed FePt nanoparticle assemblies
    (Georgia Institute of Technology, 2002-09) Zeng, Hao ; Li, Jing ; Wang, Z. L. (Zhong Lin) ; Liu, J. Ping ; Sun, Shouheng
    Thermal treatment of self-assembled FePt nanoparticles reduces the interparticle distances, resulting in dramatic changes in the type and strength of interparticle interactions. Consequently, magnetic properties such as the hysteresis and magnetization reversal mechanisms are strongly affected. It is suggested that controlled annealing of self-assembled nanoparticles may offer a novel approach for producing hard magnetic nanocomposites.