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Effects of Y211 phase contents on the critical current density J_c and microstructural analysis.in YBCo bulk superconductors

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Rare Metals 2002年第4期21卷 282-288页

作者： SHA Jianjun, YU Gang, and YU JinnanChina inst.tute of Atomic energy, p. o. box 275-51, Beijing 102413, China China inst.tute of Atomic energy P.O. Box 275-51 北京 102413

YBCo bulk superconductors were prepared by the solid state reaction andtop-seed-melt-textured growth (TSMTG) p.o.ess. By using the AC susceptibility measurement, thecritical transition temperature T_c of samples is 91.5 K for the highest value, and the transitionwidth ΔT_c is less than 1 K. The highest magnetization critical current densities J_c achieved 10~6A/cm^2 under 5 T at 10 K and 1.35X10^4 A/cm^2 under 2 T at 70 K (H//c), respectively. The resultscombining the SEM observation indicate that doping of Y211 particles is more effective in imp.o.ingthe growth quality of melt-textured YBCo superconductor and in reducing the micro-cracks ofspecimens. Doping of Y_2o_3 powder forms the rod-shaped Y211 particles, but doping of Y211 particlesdirectly to matrix materials forms the spherical Y211 particles mainly. Combining themicrostructures with J_c measurements shows that the interfaces are most important on flux bundlepinning, in which the gradient of free energy is larger than that of other place between the Y211particles and the Y123 matrix materials.

关键词： quasi-single domain melt-textured Y211 particles critical current density magnetic flux pinning

Effect of Y_2o_3 on the crystallization kinetics of Tio_2 nucleated LAS glass for the p.o.uction of nanocrystalline transparent glass ceramics

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International Journal of Minerals,Metallurgy and Materials 2013年第5期20卷 450-455页

作者： Mohammad Sadegh Shakeri Materials and energy Research Center (MERC) P.O. Box 31779-83634KarajIran

Crystallization kinetics of metastable B-quartz solid solution as a desirable phase for the p.o.uction of trans- parent lithium aluminosilicate （LAS） glass ceramics was investigated in the presence of Y203. Accordingly, differential thermal analysis.scans were performed thoroughly to study the mechanism of crystallization kinetics. The aim of this investigation is to discover the complicated mechanism of crystallization p.o.ess in the presence of co-additives and ac- cordingly find a way for increasing the transparency of glass ceramics. It is shown that the bulk （3D） growth is intensively increased by the enhancement of Y203. Then again, reducing nucleation and increasing growth mechanisms were recog- nized for the LAS system in the presence of Y2o3. Results of the investigation illustrate that when co-additives are added to glasses, it is necessary to nucleate the optical component separately before the growth p.o.ess.

关键词： glass ceramics lithium aluminosilicate yttria crystallization kinetics nanocrystals transparency

Studies on electron cloud inst.bility in BEpCⅡ

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Chinese physics C 2009年第S2期33卷 71-74页

作者：刘瑜冬岳军会王娜 inst.tute of High energy physics CAS P.O. Box 918

Electron Cloud inst.bility has been studied in the operation of BEpC. The BEpCⅡ began the commissioning in November 2006 and the positron beam current has reached 500 mA. Because of such a high beam current, some inst.bilities such as ECI, bunch lengthening et al, have appeared during the operation. The experimental investigation on ECI during the commissioning of BEpCⅡ will be reported in this paper.

关键词： electron cloud sideband coupled bunch inst.bility feedback system blow up

Simulation of Control and Guidance system for the Spinning Missile

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Journal of systems Engineering and Electronics 1994年第3期5卷 49-56页

作者： Meng Daikui (China Changfeng system Engineering Corporation, p.o.box 142-30, Beiging 100854, China) China Changfeng system Engineering Corporation P.O. Box 142-30 Beiging 100854 China

Adopted for some small-size short range surface-to-air missiles and antitank guided missiles is a single-channel control method of making missile rotating around its longitudinal axis. In hardware-in-the-loop simulations of the guidance and control system for these kinds of spinning missiles, imp.o.er use of special simulation equipment and test method will cause significant errors, even lead to failure of the simulation. In this article, the author gives an analysis.of the causes of significant errors and failure of the simulation, and puts forward a solution, which is imp.o.ed workable in making the hardward-in-the-loop simulation successful.

关键词： Computer simulation Error analysis Computer system recovery Missiles

Angular Distributions for φ＇ Sequential Decays into 2（π^＋π^-）pp^-γ via XCJ

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Communications in Theoretical physics 2005年第6X期44卷 1050-1054页

作者： pING Rong-Gang CCAST (World Lab.) P.O. Box 8730 Beijing 100080 China inst.tute of High energy physics the Chinese Academy of Sciences P.O. Box 918(1) Beijing 100049 China

Amplitudes for φ（2S） sequential decays into 2（π^＋π^-）pp^-γ via XCJ are constructed in effective coupling scheme. A Mote-Carlo simulation is carried out to study angular distributions of the decayed particles in laboratory system. The results can be taken as a reference for measuring the decay of XCJ into at BESⅡ/BEpC in the near future.

关键词： charmonium decays Monte-Carlo simulation invanant amplitudes

Comparative analysis.of ceramic-carbonate nanocomposite fuel cells using composite GDC/NLC electrolyte with different perovskite structured cathode materials

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Frontiers of Chemical Science and Engineering 2018年第1期12卷 162-173页

作者： Muhammad I. Asghar Sakari Lepikko Janne patakangas Janne Halme peter D. Lund New energy technologies Group Department of Applied Physics Aalto University P.O. BOX 15100 FI-00076 Aalto Finland

A comparative analysis.of perovskite structured cathode materials, La0.65Sr0.35Mn03 （LSM）, La0.8Sr0.2Coo3 （LSC）, La0.6Sr0.4Feo3 （LSF） and La0.6Sr0.4Co0.2Fe0.803 （LSCF）, was performed for a ceramic-carbonate nanocomposite fuel cell using composite electrolyte consisting of Gd0.1Ce0.9o1.95 （GDC） and a eutectic mixture of Na2Co3 and Li2Co3. The compatibility of these nanocomposite electrode powder materials was investigated under air, Co2 and air/Co2 atmospheres at 550 ℃. Microscopy measurements together with energy dispersive X-ray spectroscopy （EDS） elementary analysis.revealed few spots with higher counts of manganese relative to lanthanum and strontium under pure Co2 atmosphere. Furthermore, electrochemical impedance （EIS） analysis.showed that LSC had the lowest resistance to oxygen reduction reaction （oRR）（14.12 Ω·cm^2） followed by LSF （15.23 Ω·cm^2）, LSCF （19.38Ω·cm^2） and LSM （〉 300 Ω·cm^2）. In addition, low frequency EIS measurements （down to 50 gHz） revealed two additional semi-circles at frequencies around 1 Hz. These semicircles can yield additional information about electrochemical reactions in the device. Finally, a fuel cell was fabricated using GDC/NLC nanocomposite electrolyte and its composite with Nio and LSCF as anode and cathode, respectively. The cell p.o.uced an excellent power density of 1.06 W/cm^2 at 550 ℃ under fuel cell conditions.

关键词： electrode fuel cell low-temperature nano- composite perovskite

Analytical and simulation studies for diode and triode ion beam extraction systems

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Chinese physics C 2012年第4期36卷 344-349页

作者： M. M. Abdelrahman N. I. Basal S. G. Zakhary Accelerators & Ion Sources Department Nuclear Research Center Atomic Energy Authority P.O. Box: 13759 Inchas Atomic Energy Authority

This work is concerned with ion beam dynamics and compares the emittance to aberration ratios of two-and three-electrode extraction systems. The study is conducted with the aid of Version 7 of SIMIoN 3D ray-tracing software. The beam dependence on various parameters of the extraction systems is studied and the numerical results lead to qualitative conclusions. Ion beam characteristics using diode and triode extraction systems are investigated with the aid of the computer code SIMIoN 3 D, Version 7.0. The diode （two electrode extraction system） and triode （three- electrode extraction, acceleration-deceleration system） extraction systems are designed and optimized with different geometric parameters of the electrode system, voltage applied to the extraction electrode, and plasma parameters inside the ion source chamber, as well as by the ion beam space charge. This work attempts to describe the importance of the acceleration-deceleration extraction system. It shows that besides an increase of the beam energy, the ion beam has lower emittance than the two-electrode extraction system. Ion beams of the highest quality are extracted whenever the half-angular divergence is minimum for which the perveance current intensity and the extraction gap have optimum value. Knowing the electron temperature of the plasma is necessary to determine plasma potential and the exact beam energy.

关键词： ion beam emittance plasma meniscus space charge ion beam SIMIoN computer p.o.ram

CHEMICAL SpECIES oF IRIDIUM AND oTHER TRACE ELEMENTS AT K-T BoUNDARY CLAY LAYER, STEVNS KLINT, DENMARK, AND ITS IMpLICATIoN

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Science China Chemistry 1991年第12期34卷 1492-1500页

作者：柴之芳孔屏毛雪瑛马淑兰周瑶琪马建国 inst.tute of High energy physics Academia Sinica P.O. Box 2732 Beijing 100080 PRC

The chemical species of anomalous Ir in the Fish Clay K-T boundary at Stevns Klint, Denmark, was studied by using a newly-developed chemical stepwise dissolution p.o.edure and neutron activation analysis. The experimental results indicate that the anomalous Ir mostly exists in the acid-insoluble residue phase. The Ir pattern of the K-T boundary resembles that of the Ningqiang carbonaceous chondrite, while remarkably different from those of the ultrabasic rock and volcanic lava. Thus, we deduce that the Ir anomaly at K-T boundary is mainly extraterrestrial, inst.ad of volcanogenic or geochemical enrichment origin. The patterns of other trace elements in various phases also confirm the above conclusion.

关键词： K-T boundary Ir anomaly chemical species event stratigraphy.

Modeling of co-current and counter-current bubble columns with an extended EMMS app.o.ch

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particuology 2019年第3期17卷 126-135页

作者： Xiaoping Guan Ning Yang State Key Laboratory of Multi-phase Complex system Institute of Process Engineering Chinese Academy of Sciences P.O. Box 353 Beijing 100190 China

Bubble columns can be operated in semi-batch, co-current or counter-current mode. This study attempts to extend the dual-bubble-size (DBS) model, viz., the energy-minimization multi-scale (EMMS) model for gas-liquid systems, to co-current and counter-current bubble columns. With the increase of superficial liquid velocity, the predicted total gas holdup and regime transition are in accordance with experiments. A DBS drag model was then developed and incorporated into the CFD simulation. The total gas holdup and local gas holdup radial distribution in both the co-current and counter-current bubble columns are well estimated. The findings in the present work demonstrate that developing closure laws through the stability condition is of great significance in modeling complicated multi-scale flow in bubble columns.

关键词： Co-current Counter-current Bubble columns CFD Drag model