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R&D Status of High-current Accelerators at IFP
J. J. Deng,J. S. Shi,W. P. Xie,L. W. Zhang,K. Z. Zhang,S. P. Feng,J. Li,M. Wang,Y. He,L. S. Xia,Z. Y. Dai,H. T. Li,L. Wen,S. F. Chen,X. Li,Q. G. Lai,M. H. Xia,Y. C. Guan,S. Y. Song,L. Chen 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.61
High-current accelerators have many important applications in Z-pinches, high-power microwaves, and free electron lasers, imploding liners and radiography and so on. Research activities on Zpinches, imploding liners, radiography at the Institute of Fluid Physics (IFP) are introduced. Several main high-current accelerators developed and being developed at IFP are described, such as the Linear Induction Accelerator X-Ray Facility Upgrade (LIAXFU, 12 MeV, 2.5 kA, 90 ns), the Dragon-I linear induction accelerator (20 MeV, 2.5 kA, 60 ns), and the Primary Test Stand for Z-pinch (PTS, 10 MA, 120 ns). The design of Dragon-II linear induction accelerator (20 MeV, 2.5 kA, 3 × 60 ns) to be built will be presented briefly.
Elemental mercury oxidation from flue gas by microwave catalytic oxidation over Mn/g-Al2O3
Z.S. Wei,Y.W. Luo,B.R. Li,Z.Y. Chen,Q.H. Ye,Q.R. Huang,J.C. He 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.24 No.-
The integrated microwave with Mn/g-Al2O3 and ozone was employed to oxidize elemental mercury (Hg0) in simulated flue gas. Hg0 oxidation efficiency in the integrated system attained 92.2%. Mn/g-Al2O3 catalyst was characterized by XRD, XPS, FT-IR, SEM. XPS spectra indicate the formation of a stable mercuric oxide species (HgO) from mercury oxidation. Ozone molecules in air could enhance free radical formation. Hg0 was oxidized to HgO in the presence of ozone and free radical. The coupling role between ozone and radical on mercury oxidation was formed. Microwave catalytic oxidation of elemental mercury reaction with the Mn/g-Al2O3 catalyst follows Langmuir–Hinshelwood kinetics.
Etchant-induced shaping of nanoparticle catalysts during chemical vapour growth of carbon nanofibres
He, Z.B.,Maurice, J.L.,Lee, C.S.,Gohier, A.,Pribat, D.,Legagneux, P.,Cojocaru, C.S. Pergamon Press ; Elsevier Science Ltd 2011 Carbon Vol.49 No.2
Carbon nanofibres (CNFs) obtained by plasma-enhanced chemical vapour deposition are made of cone-shaped graphene layers, the opening angle of which has a significant influence on their properties: the smaller the angle, the closer the properties to those of carbon nanotubes. That angle is determined by the shape of the metal nanoparticle used to catalyse the growth. We show in this paper that the shape of Ni nanoparticle catalysts, and in turn the CNF properties, can be tuned during plasma-enhanced chemical vapour deposition, by the choice of the etchant gas. We show in particular that a water-containing etchant (H<SUB>2</SUB>O or H<SUB>2</SUB>O+H<SUB>2</SUB>) increases the growth rate by an order of magnitude at 600<SUP>o</SUP>C compared to an ammonia-containing etchant (NH<SUB>3</SUB> or NH<SUB>3</SUB>+H<SUB>2</SUB>), and leaves more elongated Ni particles with a cone angle three times smaller. We conclude that the cone angle and the growth rate are directly related, and propose a mechanism to explain that large difference between the two etchants
Time domain identification of multiple cracks in a beam
Z.Y. He,Z.R. Lu 국제구조공학회 2010 Structural Engineering and Mechanics, An Int'l Jou Vol.35 No.6
It is well known that the analytical vibration characteristic of a cracked beam depends largely on the crack model. In the forward analysis, an improved and simplified approach in modeling discrete open cracks in beams is presented. The effective length of the crack zone on both sides of a crack with stiffness reduction is formulated in terms of the crack depth. Both free and forced vibrations of cracked beams are studied in this paper and the results from the proposed modified crack model and other existing models are compared. The modified crack model gives very accurate predictions in the modal frequencies and time responses of the beams particularly with overlaps in the effective lengths with reduced stiffness. In the inverse analysis, the response sensitivity with respect to damage parameters (the location and depth of crack, etc.) is derived. And the dynamic response sensitivity is used to update the damage parameters. The identified results from both numerical simulations and experiment work illustrate the effectiveness of the proposed method.
Time domain identification of multiple cracks in a beam
He, Z.Y.,Lu, Z.R. Techno-Press 2010 Structural Engineering and Mechanics, An Int'l Jou Vol.35 No.6
It is well known that the analytical vibration characteristic of a cracked beam depends largely on the crack model. In the forward analysis, an improved and simplified approach in modeling discrete open cracks in beams is presented. The effective length of the crack zone on both sides of a crack with stiffness reduction is formulated in terms of the crack depth. Both free and forced vibrations of cracked beams are studied in this paper and the results from the proposed modified crack model and other existing models are compared. The modified crack model gives very accurate predictions in the modal frequencies and time responses of the beams particularly with overlaps in the effective lengths with reduced stiffness. In the inverse analysis, the response sensitivity with respect to damage parameters (the location and depth of crack, etc.) is derived. And the dynamic response sensitivity is used to update the damage parameters. The identified results from both numerical simulations and experiment work illustrate the effectiveness of the proposed method.
He, J.,Mattern, N.,Tan, J.,Zhao, J.Z.,Kaban, I.,Wang, Z.,Ratke, L.,Kim, D.H.,Kim, W.T.,Eckert, J. Elsevier Science 2013 ACTA MATERIALIA Vol.61 No.6
The Zr-Ce-La system is characterized by a miscibility gap and a monotectic reaction. It separates into Zr-rich and CeLa-rich liquids upon cooling through the gap. Based on this system, a new Zr-Ce-La-Al-Co monotectic system was created to synthesize liquid-phase-separated bulk metallic glasses (LPS-BMGs) by copper mold casting. A systematical investigation was performed for the effects of the relative atomic ratios of Zr:CeLa, Co:Al and Ce:La on the microstructure features and chemical compositions of the two coexistent phases. Dual atom pairs with positive heat of mixing (Zr-Ce: +12kJmol<SUP>-1</SUP> and Zr-La: +13kJmol<SUP>-1</SUP>) are originally adopted to develop such LPS-BMGs. A series of in situ formed LPS-BMGs with a critical thickness of 2.5mm has been successfully synthesized. By combining the kinetics of liquid-liquid phase separation with the formation of metallic glasses, the mechanisms of phase formation and the microstructure evolution in the rapidly cooled alloys are discussed in detail. Furthermore, a thermodynamic model is proposed for LPS-BMG design, attempting to build a bridge from monotectic/immiscible (M/I) alloys to LPS-BMGs. This work not only provides opportunities for new insights into the synthesis of LPS-BMGs and their properties but also opens new perspectives for processing and research of M/I alloys.
Experimental test on bridge jointed twin-towered buildings to stochastic wind loads
Ni, Z.H.,He, C.K.,Xie, Z.N.,Shi, B.Q.,Chen, D.J. Techno-Press 2001 Wind and Structures, An International Journal (WAS Vol.4 No.1
This paper presents results of a study on wind loads and wind induced dynamic response of bridge jointed twin-towered buildings. Utilizing the high-frequency force balance technique, the drag and moment coefficients measured in wind tunnel tests, and the maximum acceleration rms values on the top floor of towers, are analyzed to examine the influence of building's plan shapes and of intervals between towers. The alongwind, acrosswind and torsional modal force spectra are investigated for generic bridge jointed twin-towered building models which cover twin squares, twin rhombuses, twin triangles, twin triangles with sharp corners cut off, twin rectangles and individual rectangle with the same outline aspect ratio as the twin rectangles. The analysis of the statistical correlation among three components of the aerodynamic force corroborated that the correlation between acrosswind and torsional forces is significant for bridge jointed twin-towered buildings.