J. Sheng

Shanghai Jiao Tong University, Shanghai, Shanghai Shi, China

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Publications (21)31.24 Total impact

  • J. Sheng · J. Wen · Y. Wei · W. Zeng · Z. Jin · Z. Hong
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    ABSTRACT: A voltage-source finite-element model of high-temperature superconducting tapes is presented in this paper. This model is a combined model built on both MATLAB and COMSOL, and it is used to study the overcurrent characteristics of non-uniform HTS tapes. The electrical parameters, magnetic distribution, and temperature distribution are separately calculated by different software. The temperature, magnetic flux intensity, and generated heat are set as the intermediate exchange variables. The model accuracy is calibrated and verified by short-circuit experiments of a uniform five-turn HTS solenoid. Then, the basic model is expanded and used to simulate the overcurrent characteristics of nonuniform HTS tapes. Conclusions are provided by considering both simulation and experimental results from these non-uniform tapes, and the results of this study can be used for the design of superconducting devices.
    IEEE Transactions on Applied Superconductivity 06/2015; 25(3):1-5. DOI:10.1109/TASC.2014.2376181 · 1.32 Impact Factor
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    ABSTRACT: Joints play an important role in the application of YBaCuO-coated conductors. Given the limited length and various requirements of tapes, large numbers of joints are needed in some applications. Therefore, developing stable joints between tapes and achieving low joint resistance has become an important issue for the application of YBCO tapes. In this paper, we propose a novel superconducting joint production process and fabricate these joints with a lamination machine. A few meters or more than 10 m of joint overlapping length can be achieved, and the joint resistance can be as low as 2.25 nΩ when the overlapping length reaches 8 m. A series of experiments has been carried out to explore the joint resistance changing law, with overlap length increases, and the joint characteristics. The results show that joint resistance is inversely proportional to the overlap length. Although long bridge joints cost more, they have an incomparable advantage in that the joint resistance is distributed over the bridge joint, which allows for more stable operation and less liquid nitrogen boiloff. After joint lamination processing, the burnout current rises from 276 to 523 A. Critical current and joint resistance are not affected by the overcurrent before the joint burns out.
    IEEE Transactions on Applied Superconductivity 06/2015; 25(3):1-5. DOI:10.1109/TASC.2014.2365694 · 1.32 Impact Factor
  • X. Liu · J. Wen · J. Sheng · W. Zeng · J. Ma · Y. Wang · Z. Y. Li · Z. Jin · Z. Hong
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    ABSTRACT: Quenching characteristic is one of the most important characteristics of superconducting fault current limiters (SFCLs). Recently, the designs of SFCLs have been developing rapidly. Because of the influences of electrical inductance and heat dissipation, different types of SFCL could behave quite differently during quenching process. In this paper, the quenching characteristics of several different individual SFCL modules have been investigated. Special attention has been paid to the limited current and structural features between them. The elementary types of YBCO thin-film wires are solenoid and pancake. Different types of superconducting fault current limiting modules were connected in series to evaluate their advantages and disadvantages. Results in this paper could be helpful to optimize the designs of SFCLs in space utilization and energy efficiency.
    IEEE Transactions on Applied Superconductivity 06/2015; 25(3):1-5. DOI:10.1109/TASC.2014.2386312 · 1.32 Impact Factor
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    ABSTRACT: This paper focuses on no-insulation (NI) HTS pancake coils with iron core for superconducting dc induction heaters. A superconducting coil without turn-to-turn insulation and its conventional counterpart with insulation are wound with YBCO-coated tapes. An iron core is built for a laboratory-scale dc induction heater. The electromagnetic characteristics of the two coils with the iron core are studied focusing on the charging and sudden-discharging processes at 77 K. Three variables are measured, i.e., current, terminal voltage, and magnetic field induced. The results show that NI coil with the iron core incurs a significant delay in the charging and discharging process due to the influence of the iron core. A terminal voltage pulse is observed at the beginning of the sudden-discharging process, which is more than five times of its normal value. A circuit-field coupled method is proposed to analyze the electromagnetic characteristics of the NI coil with an iron core. The results from experiment and simulation exhibits good agreement. The research shows that it is possible to use the NI technique to build a HTS iron core magnet for a dc induction heater, which can simplify the quench protection system.
    IEEE Transactions on Applied Superconductivity 06/2015; 25(3):1-5. DOI:10.1109/TASC.2014.2361932 · 1.32 Impact Factor
  • J. Wen · B. Lin · J. Sheng · J. Xu · Z. Jin · Z. Hong · D. Wang · H. Zhou · X. Shen · C. Shen
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    ABSTRACT: Superconducting fault current limiter (SFCL) could reduce short circuit currents in electrical power system. One of the most important thing in developing SFCL is to find out the maximum permissible voltage of each limiting element. The maximum permissible voltage is defined as the maximum voltage per unit length at which the YBCO coated conductors (CC) do not suffer from critical current (Ic) degradation or burnout. In this research, the time of quenching process is changed and voltage is raised until the Ic degradation or burnout happens. YBCO coated conductors test in the experiment are from American Superconductor (AMSC) and Shanghai Jiao Tong University (SJTU). Along with the quenching duration increasing, the maximum permissible voltage of CC decreases. When quenching duration is 100 ms, the maximum permissible of SJTU CC, 12 mm AMSC CC and 4 mm AMSC CC are 0.72 V/cm, 0.52 V/cm and 1.2 V/cm respectively. Based on the results of samples, the whole length of CCs used in the design of a SFCL can be determined.
    Physica C Superconductivity 06/2014; 501. DOI:10.1016/j.physc.2014.03.016 · 1.11 Impact Factor
  • Y. Chen · X. Liu · J. Sheng · L. Cai · Z. Jin · J. Gu · Z. An · X. Yang · Z. Hong
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    ABSTRACT: A dc resistive type superconducting fault current limiter (SFCL) is presented in this paper. This SFCL is designed for the HVDC system. Experiments are conducted to prove the current limiting ability of superconducting materials in dc system. Uniform current and voltage sharing among the SFCL modules can be observed through contact resistance tests, dc flow-through tests, and ac flow-through tests. Results of tests show that each limiting module has good uniformity in higher current system. Then, system simulation model based on these experimental data is built in PSCAD, and simulations are carried out to determine the value of shunt resistor. Results of simulation show that SFCL has fast responding time and good current limiting performance in dc network.
    IEEE Transactions on Applied Superconductivity 06/2014; 24(3):1-5. DOI:10.1109/TASC.2013.2284936 · 1.32 Impact Factor
  • J. Wen · B. Lin · J. Sheng · L. Ying · L. Yao · Z. Jin · Z. Hong
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    ABSTRACT: In a resistive superconducting fault current limiter (SFCL), the electrodynamic force among the YBCO tapes is enormous when experiencing a high short circuit current, which may cause deformation of tapes and damage of their electrical characteristics. The purpose of this paper is to investigate how much electrodynamic force the YBCO tapes can bear. In this paper, an electrodynamic force simulation model is built to simulate the force, which the two parallel tapes experience and their deformation when short-circuit currents of different value flow through. Then we conducted experiments to observe the deformation of the tapes when they are experiencing a short-circuit current and see if the volt-ampere characteristic of the tapes has a noticeable change after that. Combining the results of the simulation and the experiments, we can obtain the electrodynamic force that tapes can bear. The result can guide us to design the layout of the tapes in the SFCL in accordance with the required fault current level.
    Journal of Superconductivity and Novel Magnetism 05/2014; 27(5). DOI:10.1007/s10948-013-2437-4 · 0.93 Impact Factor
  • J. Sheng · H. Sun · X. Liu · Z. Jin · Z. Hong
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    ABSTRACT: Over-current performance of YBa2Cu3O7-δ tapes under power frequency has been well-studied by previous researches. However, in power grid, superconducting apparatus will also experience lightning impulse current under special working conditions. In this paper, two kinds of lightning impulse current are applied to superconducting testing samples. Comparisons between superconducting characteristics before and after the testing are presented in this paper. Explanations of performance degradation are presented from both the perspectives of temperature and stress mathematic calculation. A maximum endurable value of lightning current which may not cause degradation is obtained from the testing results.
    Applied Physics Letters 03/2014; 104(11):112602-112602-4. DOI:10.1063/1.4868639 · 3.52 Impact Factor
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    ABSTRACT: This paper presents a study of frequency dependence of the overcurrent characteristics of high-temperature superconducting (HTS) tape. Fault currents with different amplitudes and frequencies are applied to HTS tape, and the relationship between the overcurrent characteristics and current parameters are obtained after processing and analyzing the experimental results. In addition, a phase difference between the current peak and voltage peak is found in these experiments. Using both simulations and experiments, studies are carried out to find the reason for this phenomenon. Conclusions given in this paper provide useful information for optimizing the design of superconducting apparatus.
    IEEE Transactions on Applied Superconductivity 01/2014; 25(3):1-1. DOI:10.1109/TASC.2014.2371924 · 1.32 Impact Factor
  • J Sheng · X Qu · X Zhang · Z Zhai · H Li · X Liu · G Liu · Z Zhu · Y Hao · A Qin · K Dai
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    ABSTRACT: The present meta-analysis shows no clear association between coffee consumption and the risk of hip fractures. There was a nonlinear association between tea consumption and the risk of hip fracture. Compared to no tea consumption, drinking 1-4 cups of tea daily was associated with a lower risk of hip fracture. Prospective cohort and case-control studies have suggested that coffee and tea consumption may be associated with the risk of hip fracture; the results have, however, been inconsistent. We conducted a meta-analysis to assess the association between coffee and tea consumption and the risk of hip fracture. We performed systematic searches using MEDLINE, EMBASE, and OVID until February 20, 2013, without limits of language or publication year. Relative risks (RRs) with 95 % confidence intervals (CI) were derived using random-effects models throughout all analyses. We conducted categorical, dose-response, heterogeneity, publication bias, and subgroup analyses. Our study was based on 195,992 individuals with 9,958 cases of hip fractures from 14 studies, including six cohort and eight case-control studies. The pooled RRs of hip fractures for the highest vs. the lowest categories of coffee and tea consumption were 0.94 (95 % CI 0.71-1.17) and 0.84 (95 % CI 0.66-1.02), respectively. For the dose-response analysis, we found evidence of a nonlinear association between tea consumption and the risk of hip fracture (p nonlinearity < 0.01). Compared to no tea consumption, 1-4 cups of tea per day may reduce the risk of hip fracture by 28 % (0.72; 95 % CI 0.56-0.88 for 1-2 cups/day), 37 % (0.63; 95 % CI 0.32-0.94 for 2-3 cups/day), and 21 % (0.79; 95 % CI 0.62-0.96 for 3-4 cups/day). We found no significant association between coffee consumption and the risk of hip fracture. A nonlinear association emerged between tea consumption and the risk of hip fracture; individuals drinking 1-4 cups of tea per day exhibited a lower risk of hip fractures than those who drank no tea. The association between 5 daily cups of tea, or more, and hip fracture risk should be investigated.
    Osteoporosis International 11/2013; 25(1). DOI:10.1007/s00198-013-2563-7 · 4.17 Impact Factor
  • Y. Chen · S. Li · J. Sheng · Z. Jin · Z. Hong · J. Gu
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    ABSTRACT: Superconducting fault current limiter (SFCL) has become one of the most ideal current limiting devices to solve the problem of increasing short-circuit current in high-voltage power grid. This paper presents a resistive-type SFCL model developed using simulation software PSCAD/EMTDC. After being verified by finite-element model and experimental results, the model is used to study the impact of SFCLs on the power grid and the co-ordination between SFCL and relay protections in 10 kV distribution network. A series of simulations are carried out to find appropriate parameters of SFCL model to cooperate with relay protection devices. The final result in this paper could provide important quantitative basis of parameters for SFCL to be applied in a real power system.
    Journal of Superconductivity and Novel Magnetism 11/2013; 26(11). DOI:10.1007/s10948-013-2181-9 · 0.93 Impact Factor
  • Z. Hong · J. Sheng · L. Yao · J. Gu · Z. Jin
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    ABSTRACT: This paper presents the design and performance test of a 10 kV, 200 A resistive type superconducting fault current limiter prototype. This is the continued study of the test towards an individual current limiting module, which was done and published in August 2011. The construction of the whole prototype including the cryostat has finished. A series of tests including short circuit test, recovery test, auto-reclosure test, and LN2 boiling test have been performed and the results are presented in this paper. This single phase superconducting fault current limiter is made from 15 current limiting modules. Several 1-m long YBCO coated conductors prepared by Shanghai Jiaotong University are used to build the current limiting module. Each module has 2 tapes connected in parallel to carry 200 A rated current (Ic of each tape is about 150 A) and 6 tapes connected in series to withstand 700 ~ 800 V voltage drop.
    IEEE Transactions on Applied Superconductivity 06/2013; 23(3):5601304-5601304. DOI:10.1109/TASC.2012.2231899 · 1.32 Impact Factor
  • L. Ying · J. Xu · J. Sheng · B. Lin · Z. Jin · Z. Hong · Zhuyong Li
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    ABSTRACT: Because of the complexity of the electrical system, dc offset current and ac ripple current have generally existed. However, they are usually undesirable, and their influence to ac loss is also an important issue for superconducting devices built from YBaCuO-coated conductors. In this paper, ac loss of YBCO tapes with nonmagnetic substrate carrying dc or ac offset current have been both measured and calculated. Experiments based on “electrical method” composed of a high-performance amplifier and a wave recorder with filtering function has been carried out. To verify the measurement, a two-dimensional finite element method model based on finite element method and power law is applied to calculate the ac loss with current combined with ac and dc components. The results show that, a small value of dc offset current in a large ac component has minor effect to the ac loss. In addition, when the total current (combined with ac and dc components) approaches critical value, the ac loss would increase significantly.
    IEEE Transactions on Applied Superconductivity 06/2013; 23(3):5900704-5900704. DOI:10.1109/TASC.2013.2245373 · 1.32 Impact Factor
  • S. Li · J. Sheng · Y. Chen · Z. Jin · Y. Yin · L. Yao · Z. Hong
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    ABSTRACT: In superconducting power apparatus, electric insulation is one of the most important deciding factors on their performance. Bubbles produced during quench condition of superconducting tapes will degrade the insulation performance of liquid nitrogen and reduce the electrical breakdown voltage of the apparatus. This paper presents the bubble behavior and the influence on insulation properties of liquid nitrogen ( LN2) for superconducting power apparatus. The result will provide useful information for superconducting power devices in transmission voltage level, such as fault current limiter, transformers, and cables. Measurements are made to get the ac breakdown voltages in LN2 using spherical brass electrodes as quasi-uniform electric field. Different structures of HTS tapes are used as electrodes to simulate real working conditions. Bubbles are created by heaters, and their influences on the breakdown voltage are measured. How the breakdown strength would be affected by the bubbles is studied by changing the length of the gap of electrodes and the amount of bubbles. Breakdown voltage of G10 slice is also tested. Experiments show that the breakdown strength of LN2 is sensitive to the behavior of bubbles. Different structures of HTS tape have different breakdown properties under bubbling condition. G10 material is a good choice to provide insulation strength between HTS tapes.
    IEEE Transactions on Applied Superconductivity 06/2013; 23(3):5000205-5000205. DOI:10.1109/TASC.2012.2236371 · 1.32 Impact Factor
  • L. Yang · M. Xing · L. Zhang · J. Sheng · Z. Bao
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    ABSTRACT: Spotlight synthetic aperture radar (SAR) is an effective way to obtain finer azimuth resolution than the achievement in strip-map mode with the same physical antenna. In general, for spotlight SAR imaging, high azimuth resolution requires long synthetic aperture length. However, in practical airborne applications, because of the inevitable atmospheric turbulence during the long flight trajectory, more complicated motion error is induced that severely degrades the focusing quality of the SAR image. It makes motion compensation (MOCO) for high-resolution spotlight (HR-Spotlight) SAR imagery more difficult than that for other SAR systems. To tackle the HR-Spotlight SAR data contaminated by the complicated motion error, a novel MOCO algorithm based on entropy minimisation is proposed, which is named by minimum entropy MOCO (ME-MOCO). In this approach, by fitting a polynomial to the motion error, the entropy of a focused image is utilised as the optimisation function of the polynomial coefficients. Attributed to damped Newton method, a modified strategy is designed, which results in that the data-driven ME-MOCO algorithm estimates high order polynomial parameters accurately and efficiently. Besides, the proposed algorithm is efficient for the capability of exploiting the fast Fourier transform through the processing chain. Real data experiments and comparisons demonstrate the effectiveness and superiority of the proposal.
    IET Radar Sonar ? Navigation 08/2012; 6(7):627-637. DOI:10.1049/iet-rsn.2011.0078 · 1.03 Impact Factor
  • J. Sheng · Z. Jin · B. Lin · L. Ying · L. Yao · J. Zhang · Y. Li · Z. Hong
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    ABSTRACT: A multi-physics finite element model of high temperature superconductors (HTS) is presented in this article. An electrical model based on a set of Maxwell's equations and E-J power law is used to solve the critical state of the superconductor. A heat transfer model is added to the electrical model to calculate the temperature distribution and therefore investigate the Jc (T) dependence of the superconductor. The model is used to study the quench behavior of YBCO-coated conductors for the application of resistive type fault current limiters. Some numerical techniques are applied and assumptions are made to simplify the calculation and improve convergence. An equivalent heat transfer coefficient which is much larger than the normal heat transfer coefficient is applied to the region surrounding the superconductors. This equivalent coefficient represents the drastic heat exchange during the boiling of the liquid nitrogen. The cross-section of YBCO tapes is divided into several sub-domains. The temperature is assumed to be uniform in each sub-domain. This simplification significantly improves the convergence of model and still is able to keep a reasonable level of accuracy. The model is then able to simulate the whole process of YBCO tapes quenching and recovering to superconducting state. The numerical results are compared with the fault current experiments and excellent agreement is obtained.
    IEEE Transactions on Applied Superconductivity 06/2012; 22(3):56020-. DOI:10.1109/TASC.2011.2178576 · 1.32 Impact Factor
  • Z. Hong · J. Sheng · J. Zhang · B. Lin · L. Ying · Y. Li · Z. Jin
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    ABSTRACT: This paper presents the design of a 10 kV, 200 A resistive type superconducting fault current limiter prototype. Several one-meter long YBCO coated conductors prepared by Shanghai Jiaotong University are used to build the current limiting module. Each module has 2 tapes connected in parallel to reach 400 A rated current ( of each tape is 150 A ~200 A) and 6 tapes connected in series to withstand 700~800 V voltage drop. A series of tests and measurements have been carried out to investigate the performance of the fault current limiting module. Short circuit test of the module has been performed on a specially designed transformer which is able to withstand large current on the secondary side. The power capacity of the lab allows performing the test up to 40 V and a few thousand Amperes. The whole process of a fault, including fault occurring, current limiting, circuit breaker opening and superconductors recovery, has been tested and the current and voltage of YBCO tapes are monitored. The current limiting module is tested with different shunt resistors to demonstrate its ability to vary its limited current.
    IEEE Transactions on Applied Superconductivity 06/2012; 22(3):56005-. DOI:10.1109/TASC.2011.2180278 · 1.32 Impact Factor
  • B. Lin · L. Ying · J. Sheng · J. Zhang · L. Yao · Y. Li · Z. Jin · Z. Hong
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    ABSTRACT: Voltage tolerance during quench is one of the most important parameters for YBCO-coated conductors, especially for resistive type superconducting fault current limiter (SFCL) applications. How much voltage can be sustained per unit length of YBCO tape when experiencing fault current indicates the total required amount of the tapes to construct a resistive SFCL. In this paper, a step-down transformer is used to provide the short-current. As the voltage of the secondary side is not continuously variable, we change the voltage per unit length of the YBCO tape by varying the length of the tape. And the effect of the duration of short-current is also considered. A series of test have been performed to determine the maximum voltage drop that each YBCO tape can stand at fault current. The V-t curve has been measured after the tape experiencing successive quenches. Through a large number of experiments we will acquire the maximum endurable quenching voltage per unit length of YBCO tapes when experiencing short-current for different durations. The results presented in this paper would provide useful information for optimizing the design of a resistive SFCL.
    IEEE Transactions on Applied Superconductivity 06/2012; 22(3):5602904-5602904. DOI:10.1109/TASC.2011.2178380 · 1.32 Impact Factor
  • L. Ying · J. Sheng · B. Lin · L. Yao · J. Zhang · Z. Jin · Y. Li · Z. Hong
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    ABSTRACT: Heat loss is one of the most important issues for resistive type superconducting fault current limiters (SFCL) built from YBaCuO-coated conductors. A newly designed 400 V SFCL module by Smart Grid Center, Shanghai Jiaotong University (SJTU) is tested and modeled in order to get a clear understanding of its characteristics of heat losses. Two main losses, including AC loss of superconducting tapes and the losses due to contact resistance inside the SFCL module are investigated. Experiments based on “electrical method” are set up to measure the AC loss at 77 K with lock-in amplifier conditions. Meanwhile, losses from the contact resistance are calculated by analyzing their V-I curve. To better understand the behavior of the AC loss in SFCL module and verify the accuracy of the experimental results, modeling analysis is performed by means of a 2-dimensional finite element modeling (FEM). Numerical results show that the results are very close to what we get from experimental method. Detailed results will be presented and the heat losses of 10 kV SFCL consisting of about 25 modules in series are going to be discussed.
    IEEE Transactions on Applied Superconductivity 06/2012; 22(3):5602204-5602204. DOI:10.1109/TASC.2011.2180294 · 1.32 Impact Factor
  • Source
    Z. Hong · Z. Jin · M. Ainslie · J. Sheng · W. Yuan · T.A. Coombs
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    ABSTRACT: YBaCuO-coated conductors offer great potential in terms of performance and cost-saving for superconducting fault current limiter (SFCL). A resistive SFCL based on coated conductors can be made from several tapes connected in parallel or in series. Ideally, the current and voltage are shared uniformly by the tapes when quench occurs. However, due to the non-uniformity of property of the tapes and the relative positions of the tapes, the currents and the voltages of the tapes are different. In this paper, a numerical model is developed to investigate the current and voltage sharing problem for the resistive SFCL. This model is able to simulate the dynamic response of YBCO tapes in normal and quench conditions. Firstly, four tapes with different J<sub>c</sub>'s and n values in E - J power law are connected in parallel to carry the fault current. The model demonstrates how the currents are distributed among the four tapes. These four tapes are then connected in series to withstand the line voltage. In this case, the model investigates the voltage sharing between the tapes. Several factors that would affect the process of quenches are discussed including the field dependency of J<sub>c</sub>, the magnetic coupling between the tapes and the relative positions of the tapes.
    IEEE Transactions on Applied Superconductivity 07/2011; 21(3-21):1198 - 1201. DOI:10.1109/TASC.2010.2091232 · 1.32 Impact Factor

Publication Stats

54 Citations
31.24 Total Impact Points

Institutions

  • 2011–2014
    • Shanghai Jiao Tong University
      • • School of Electronic, Information and Electrical Engineering
      • • Department of Electrical Engineering
      • • Department of Electronic Engineering
      Shanghai, Shanghai Shi, China
  • 2013
    • Renji Hospital
      Shanghai, Shanghai Shi, China
  • 2011–2012
    • Xidian University
      Ch’ang-an, Shaanxi, China