Jun Hu

Shanghai Institute of Applied Physics, Shanghai, Shanghai Shi, China

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Publications (190)483.86 Total impact

  • Xue Fen · Jun Hu · Shan X. Wang · Jinliang He
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    ABSTRACT: In this paper, we report on the new design of an electric field sensor based on piezoelectric bending effect in a capacitive-sensing method. The bipolar electric field sensor with a range from −22 to 22 kV/cm concentrates on a bending structure to enlarge the piezoelectric effect and to control its bending orientation. It performs with a much higher sensitivity of 0.448 pF/(kV/cm) or 5.78%/(kV/cm) and has a better resolution of 7.0 V/cm at $E=0$. Factors influencing the capacitance response are also discussed, which might further optimize the sensitivity. Moreover, the analytical model and experimental results make an agreement on the reasonability of this electric field sensor, gaining an insightful guide to the potential capacitive-sensing electric field chip sensor widely distributed in sensor networks.
    IEEE Transactions on Industrial Electronics 09/2015; 62(9):1-1. DOI:10.1109/TIE.2015.2414397 · 6.50 Impact Factor
  • Xiao Yang · Jinliang He · Jun Hu
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    ABSTRACT: Silicone composite filled with zinc oxide microvaristors possesses excellent nonlinear conducting behavior as ZnO varistor does. For better adjusting the composite's electrical behavior to satisfy the practical field-grading requirement, this article studied the influence of ZnO filler's property on the nonlinearity of the composite. Several groups of ZnO-silicone composite samples in different filler volume fraction and filler diameter were prepared, the measured J-E characteristics show that the percolation threshold of ZnO-silicone composite is around 35%, above which the composites present reliable nonlinear behavior. The switching voltage of the composite exhibits a considerable decrease as filler's diameter increases or filler's volume fraction increases, while the nonlinear coefficient remains stable. Moreover, filler's size also has a little influence on composite's percolation limit. The conclusion above fits very well with the theory of the conducting composites and percolation process. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42645.
    Journal of Applied Polymer Science 07/2015; DOI:10.1002/app.42645 · 1.64 Impact Factor
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    ABSTRACT: An advanced metering and monitoring system based on autonomous, ubiquitous and maintenance-free wireless sensor networks is of great significance to the smart grid. However, the power supply for sensor nodes (especially those installed on high-voltage side) remains one of the most challenging issues. To date, miniaturized, reliable, low-cost and flexible designs catering the massive application of self-powered sensor nodes in the smart grid are still limited. This paper presents a nonintrusive design of power supply to support the sensor network applied in the smart grid. Using a cantilever-structured magnetoelectric (ME) composite, the energy harvester is able to scavenge energy from the power-frequency (50 Hz) magnetic field distributed around the transmission line. Design considerations for this specific type of scavenger have been discussed, and optimized energy harvester prototypes have been fabricated, which are further tested on a power line platform. Experimental results show that the single-cell and double-cell energy harvesters are capable of producing 0.62 mW and 1.12 mW at 10 A, respectively, while corresponding power outputs are enhanced to 4.11 mW and 9.40 mW at 40 A. The good energy harvesting ability of this particular ME composite indicates its great potential to make a nonintrusive, miniaturized, flexible and cost-effective power supply, which possesses great application prospects in the smart grid.
    IEEE Transactions on Industrial Electronics 07/2015; 62(7):4398-4407. DOI:10.1109/TIE.2014.2383992 · 6.50 Impact Factor
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    ABSTRACT: This experimental study reported electrical properties of linear low density polyethylene (LLDPE)/MgO nanocomposites, which were prepared by melt blending methods. The effects of surface modified MgO nanoparticles on the microstructure, space charge distribution, thermally stimulated current and DC breakdown strength of the nanocomposites were investigated. The addition of surface modified nanoparticles increases the amount of spherulites and decreases their sizes. It is found that the LDPE/MgO interface shows significant influence on electrical properties of nanocomposites. The addition of MgO nanoparticles is available to suppress the production of space charges and enhance the DC breakdown strength, depending on the loading levels of nanoparticles. Thermally stimulated currents of nanocomposites reveal strong correlation between the traps and electrical properties of nanocomposites. It is believed that this study would provide important hint to design and develop advanced polymer nanocomposites for dielectric applications, in particular the HVDC applications.
    IEEE Transactions on Dielectrics and Electrical Insulation 06/2015; 22(3):1512-1519. DOI:10.1109/TDEI.2015.7116346 · 1.23 Impact Factor
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    ABSTRACT: The application of giant magnetoresistance (GMR) current sensors in power grid and other industrial fields has a great prospect benefitting from their wide bands, high sensitivity, and good linearity. This paper studies the influence of mobile ions on current measurement of GMR sensor under high external electric field. The R-H curves of GMR multilayer sensor were depicted when the external electric and magnetic fields were both changed under three orthogonal electric field orientations. The experiment results indicate slightly varying resistances of GMR sensor when the external electric field was changed, and simulation analysis reveals that the resistance variation is attributed to the movement of surface ions under high external electric field. Therefore, a Faraday box is essential for GMR sensors to avoid interferences under high-strength field conditions, which is especially significant for their application as current sensors of the power grid.
    Journal of Applied Physics 05/2015; 117(17):17A307. DOI:10.1063/1.4907698 · 2.19 Impact Factor
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    ABSTRACT: Wireless sensors capable of scavenging energy from ambient environment have been increasingly attractive for their outstanding merits of self-sufficient and maintenance-free. This paper presents a specific design of magnetic energy harvester based on a piezoelectric/magnet composite and a magnetic concentrator. With the employment of concentrator, the energy harvesting properties have been greatly improved, which is theoretically analyzed and experimentally demonstrated with the 35 times power enlargement. The fabricated prototype with a 3 cm air-gap concentrator harvests 326 μW power at 10 Arms, which enables sufficient and reliable power supply for a wide range of low-power sensors.
    Journal of Applied Physics 05/2015; 117(17):17A304. DOI:10.1063/1.4906964 · 2.19 Impact Factor
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    ABSTRACT: A magnetoelectric (ME) composite cantilever consisting of two shear-mode Pb(Zr,Ti)O3 unimorphs and a tip NdFeB permanent magnet has been demonstrated to exhibit strong ME coupling based on the superior d 15 shear response of the piezoelectric phase. The static ME coefficient and the power density under resonance condition of the fabricated samples reach 300 mV/cm·Oe and 2.25 μW/cm3·Oe2, respectively, without demand for DC bias field, which make it outperform previous designs of shear-mode ME composites. These good properties of the ME composite cantilever promise its prospects as a miniature device for sensing, transducing, and energy harvesting applications.
    Applied Physics Letters 05/2015; 106(18):182901. DOI:10.1063/1.4919738 · 3.52 Impact Factor
  • Jinliang He · Chenlu Cheng · Jun Hu
    Scripta Materialia 04/2015; 104. DOI:10.1016/j.scriptamat.2015.03.019 · 2.97 Impact Factor
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    ABSTRACT: This paper evaluates the microstructure and properties of polypropylene/polyolefin elastomer (PP/POE) blends for potential recyclable HVDC cable insulation applications. PP/POE blends with different POE content were prepared by melt mixing. The introduction of POE results in a slight decrease of the melting points but improves the flexibility of PP. Compared with PP, the volume resistivity of the blends shows a decrease at low loading of POE and starts to increase when the POE loading is higher than 15 wt%. After the introduction of POE, the DC breakdown strength is slightly decreased and the hetero space charge accumulation is enhanced. Although the electrical properties of the PP/POE blends are inferior to those of the pure PP, the enhanced flexibility, high volume resistivity, high breakdown strength as well as the excellent thermal properties make the PP/POE blends have the potential for HVDC cable application. The hetero space charge accumulation is still an issue, and further modification of the blends should be considered for suppressing the space charges.
    IEEE Transactions on Dielectrics and Electrical Insulation 04/2015; 22(2):673-681. DOI:10.1109/TDEI.2015.7076762 · 1.23 Impact Factor
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    ABSTRACT: In the past years the self-assembly of amyloid-like peptides has attracted increasing attentions, because it is highly related to neurodegenerative diseases and has a potential for serving as nanomaterial to fabricate novel and useful nanostructures. In this paper, we focused on the role of interfacial conditions in the self-assembly of an amyloid-like peptide, termed Pep11. It was found that, when dissolved in bulk solutions, Pep11 formed into β-sheet structures and assembled into long filaments in several hours, as revealed by Thioflavin T fluorescence and transmission electron microscopy (TEM) morphology characterization, respectively. When the peptide solution was added onto a mica/HOPG substrate, peptide filaments with three preferred orientations with an angle of 60° to each other were formed immediately, as imaged in situ by atomic force microscopy (AFM). However, the kinetics in filament formation and the morphologies of the formed beta sheet either on HOPG and mica or in bulk solutions were quite different. These results indicate that the interfacial properties dramatically affect the peptide self-assembly process. Microsc. Res. Tech., 2015. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.
    Microscopy Research and Technique 03/2015; 78(5). DOI:10.1002/jemt.22483 · 1.17 Impact Factor
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    Fen Xue · Jun Hu · Shan X. Wang · Jinliang He
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    ABSTRACT: The converse magnetoelectric (CME) effect, a coupling effect resulted from compositing piezoelectric phase and piezomagnetic phase, is explored insightfully concerned with applying chip-scale CME composite into extensive electric field measurement. To establish the in-plane longitudinal CME effect, comparable mathematical models elastomechanical tensile model and elastomechanical flexural model are proposed. Grounded on generalized theoretical frameworks, the models utilized some classical magnetoelectric modeling methods. Furthermore, groups of CME composite are taken as examples to simulate and experiment for consistency verification. What highlights in the proposed models is for the purpose of forecasting and evaluating the most favorable composite and structure for CME effect applied in sensing wide range electric field.
    Applied Physics Letters 02/2015; 106(8):082901. DOI:10.1063/1.4913619 · 3.52 Impact Factor
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    ABSTRACT: This paper reports a cylindrical shear-mode magnetoelectric (ME) composite developed based on a Pb(Zr,Ti)O3 (PZT) tube bonded with an NdFeB permanent magnet for magnetic coupling. The existence of a significant ME effect originating from the superior d15 electromechanical response of the piezoelectric phase is theoretically predicted and experimentally observed with a voltage coefficient of 28.8 mV/Oe (RMS) outside resonance and a maximum power density of 4.56 μW (cm3Oe2)−1 at resonance, which are much higher than previous shear-mode ME composites without bias field in the literature. These suggest broad application prospects of this particular ME composite as magnetic sensors, transducers and energy harvesters.
    Journal of Physics D Applied Physics 02/2015; 48(4):045001. DOI:10.1088/0022-3727/48/4/045001 · 2.72 Impact Factor
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    ABSTRACT: In the fabrication of linear MTJ sensors, the utilization of magnetic bias field along the easy-axis direction makes the response of MTJ nonlinear, and the Neel and magnetostatic coupling usually induces a strong interlayer coupling field along the hard-axis direction. In this paper, we investigated the influence of hard-axis and easy-axis bias field on the linearity of MTJ magnetic sensor. The prediction and optimization of linearity were done by applying an appropriate hard-axis bias field in the specific easy-axis bias field and practical TMR ratio, and the model was verified by experiments. This work can give guidance to improve the linearity and to maximize the practical TMR ratio of the MTJ sensors under a given linearity requirement.
    IEEE Transactions on Magnetics 01/2015; DOI:10.1109/TMAG.2015.2439152 · 1.21 Impact Factor
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    ABSTRACT: Current sensing based on the giant magnetoresistance (GMR) effect has been gaining attention due to its outstanding merits. In this paper, hysteretic models of the output characteristics of GMR sensors are presented, and corresponding algorithms are successfully applied to practical GMR sensors to compensate for measurement error due to hysteresis, which is particularly important for high-frequency applications. A 91% decrease in nonlinear error is achieved by the proposed advanced hysteretic model, and the applicable frequency range of the GMR sensor can be extended to around the cutoff frequency of sensor hardware, which is nearly 50 times larger than that based on the conventional linear models. This paper provides optimized solutions for GMR current sensors in different frequency ranges.
    IEEE Transactions on Industrial Electronics 01/2015; 62(1):516-524. DOI:10.1109/TIE.2014.2326989 · 6.50 Impact Factor
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    ABSTRACT: The charge migration on the surface of single layer graphene oxide (GO) sheets was investigated by scanning polarization force microscopy. Electrostatic charges were observed to transfer over 1 μm across the insulating single layer GO sheets surface with the help of water molecules condensed from the environment. Humidity-dependent charge migration on GO sheets was visualized on the nanometer scale and the migration velocity was plotted at a relative humidity range of 10%–40%. When the relative humidity reached 50% or higher, water film would form on the whole GO sheet surface, which made the GO sheet conductive to the electrostatic charges.
    Applied Physics Letters 12/2014; 105(23):233107. DOI:10.1063/1.4903836 · 3.52 Impact Factor
  • Chunhai Fan · Jun Hu · Zhentang Zhao
    Advanced Materials 12/2014; 26(46):7685-7. DOI:10.1002/adma.201404134 · 17.49 Impact Factor
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    ABSTRACT: The magnetic tunnel junction (MTJ) effect has been widely applied in information technology and has brought about many revolutionary products in the past decade. In the meantime, many research studies on linear magnetoresistive sensors based on MTJ have been published to improve their performance metrics, such as linear field range, sensitivity, hysteresis, and noise. Though the frequency response of high-speed magnetic reading has been researched, the performance and application of linear magnetoresistive sensors with bridge configuration for high-frequency sensing remain underexplored. In this paper, we proposed an equivalent impedance network model of packaged linear magnetoresistive sensors based on MTJ with Wheatstone bridge configuration, and derived the corresponding frequency-dependent performance model, considering the influences of the parasitic capacitances and the amplitude of the applied magnetic field. Our work shows that the frequency characteristics of linear magnetoresistive sensors are closely associated with their RC time constants, which depends on their resistances and parasitic capacitances. The useful bandwidth of an MTJ linear sensor is also related to the amplitude of the applied magnetic field. The bandwidth changes negligibly with the varying magnetic field in the range of less than 30% of the saturation field, but increases rapidly when it exceeds 30% of the saturation field.
    IEEE Transactions on Magnetics 11/2014; 50(11):1-4. DOI:10.1109/TMAG.2014.2331369 · 1.21 Impact Factor
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    ABSTRACT: Herein, a novel low-temperature plasma technique was adopted to graft β-cyclodextrin (β-CD) on the surfaces of magnetic MWCNT/iron oxide particles. The as-prepared CD/MWCNT/iron oxides exhibited high saturation magnetization and good physicochemical stability in solution. Batch experiments and X-ray absorption fine structure (XAFS) spectral technique were combined to verify the removal performance and the underlying mechanisms of CD/MWCNT/iron oxides towards Ni(II) from single-solute system and the simulated Ni(II)-bearing effluent. The sorption kinetics of Ni(II) on CD/MWCNT/iron oxides can achieve equilibrium in a time period of 4 h. The surface-coated β-CD improves the dispersion property of CD/MWCNT/iron oxides and therefore enhances its removal performance towards Ni(II). The maximum sorption capacity of Ni(II) on CD/MWCNT/iron oxides is higher than a series of adsorbent materials. XAFS analysis suggests that Ni(II) can bind on the hydroxyl sites on the surface-coated β-CD and also the FeO6 octahedra of iron oxides in an edge-shared mode, forming strong inner-sphere complexes with high thermodynamic stability. Considering its high physicochemical stability, high removal performance, high separation convenience and favorable regeneration property, the prepared CD/MWCNT/iron oxides can support long-term use as a cost-effective material in the purification of Ni(II)-bearing effluents.
    Chemical Engineering Journal 11/2014; 256:128–136. DOI:10.1016/j.cej.2014.06.109 · 4.32 Impact Factor
  • Chenlu Cheng · Jun Hu · Jinliang He
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    ABSTRACT: Delicately fabricated ZnO bicrystals of varying nonlinearity, along with as-grown ZnO single crystal, are investigated by broadband dielectric spectroscopy to reveal the rate process involved in individual grain boundary and grain of ZnO electroceramics. Two types of low frequency dispersion phenomena, originating from the transport across the interface of double-Schottky barrier, present in individual grain boundaries. Investigation on the temperature dependence of loss peak frequency of bicrystal samples which obeys the Arrhenius law reveals that intrinsic donor species Zn-i(center dot) and Zn-i(center dot center dot) may contribute to the occurrence of loss peaks.
    Materials Letters 10/2014; 132:240-242. DOI:10.1016/j.matlet.2014.06.100 · 2.27 Impact Factor
  • Chenlu Cheng · Jinliang He · Jun Hu
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    ABSTRACT: The migration and neutralization of charged defect ions during the degradation of a double-Schottky barrier are observed by performing nondestructive pulsed electroacoustic measurements on ZnO bicrystals. This offers the possibility to experimentally access the predicted defect migration behavior and provides a solid foundation to validate the theoretical aging model for electroceramics. Theoretical modeling of the acoustic attenuation effects during measurements is also discussed to understand and validate the experimental results, gaining insight into the widely used acoustic technique.
    Applied Physics Letters 09/2014; 105(13):133508-133508-4. DOI:10.1063/1.4897152 · 3.52 Impact Factor

Publication Stats

3k Citations
483.86 Total Impact Points

Institutions

  • 2010–2015
    • Shanghai Institute of Applied Physics
      Shanghai, Shanghai Shi, China
  • 2007–2015
    • Tsinghua University
      • • Department of Electrical Engineering
      • • School of Life Sciences
      • • School of Medicine
      • • Department of Electronic Engineering
      Peping, Beijing, China
  • 2008–2014
    • Hefei Institute of Physical Sciences, Chinese Academy of Sciences
      Luchow, Anhui Sheng, China
    • Wuhan University
      Wu-han-shih, Hubei, China
  • 2003–2013
    • Chinese Academy of Sciences
      • • Key Laboratory of Pathogenic Microbiology and Immunology
      • • State Key Laboratory of Polymer Physics and Chemistry
      • • Graduate School
      • • State Key Laboratory of Plant Genomics
      • • Dalian Institute of Chemical Physics
      • • Laboratory of Plant Biotechnology
      Peping, Beijing, China
  • 2012
    • University of Science and Technology of China
      • School of Nuclear Science and Technology
      Luchow, Anhui Sheng, China
  • 2009–2011
    • North China Electric Power University
      Peping, Beijing, China
  • 2006
    • Dalian Institute of Chemical Physics
      Lü-ta-shih, Liaoning, China