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Effect of excitation current intensity on mechanical properties of ZL205A castings solidified under a traveling magnetic field 被引量:3
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作者 Xue-yi Fan Liang Wang +6 位作者 Zhi-qiang Du Yan-qing Su Jian-bing Zhang Liang-shun Luo Zu-chuan Liu Da-ming Xu Jing-jie Guo 《China Foundry》 SCIE CAS 2015年第3期196-201,共6页
The effect of excitation current intensity on the mechanical properties of ZL205 A castings solidified under a traveling magnetic field was studied. The results of the experiment indicate that the excitation current i... The effect of excitation current intensity on the mechanical properties of ZL205 A castings solidified under a traveling magnetic field was studied. The results of the experiment indicate that the excitation current intensity of the traveling magnetic field has a great influence on the mechanical properties of the ZL205 A castings. When the excitation current intensity is 15 A, the tensile strength and elongation of ZL205 A alloy castings increase 27.2% and 67.7%, respectively, compared with those of the same alloy solidified under gravity. The improvement of mechanical properties is attributed to the decrease of micro-porosity in the alloy. Under the traveling magnetic field, the feeding pressure in the alloy melt before solidification can be enhanced due to the electromagnetic force. Moreover, the melt flow induced by the traveling magnetic field can decrease the temperature gradient. The feeding resistance will be increased because the temperature gradient decrease. So traveling magnetic field has an optimum effect on feeding. 展开更多
关键词 TMF ZL205A alloy excitation current intensity mechanical properties optimum effect
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Dependence of Nonlinear Optical Response of Anatase TiO2 on Shape and Excitation Intensity
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作者 郭路华 王迎威 +2 位作者 蒋永强 肖思 何军 《Chinese Physics Letters》 SCIE CAS CSCD 2017年第7期266-270,共5页
Nonlinear optical (NLO) properties of anatase TiO2 with nanostructures of nanopaxticle (NP), nanowire (NW) and annealed nanowire (NWA) are studied by open-aperture and closed-aperture Z-scan techniques with a ... Nonlinear optical (NLO) properties of anatase TiO2 with nanostructures of nanopaxticle (NP), nanowire (NW) and annealed nanowire (NWA) are studied by open-aperture and closed-aperture Z-scan techniques with a fem- tosecond pulsed laser at wavelengths of 532 nm and 780 nm simultaneously. At 532 nm, when increasing excitation intensity, NLO absorption of TiO2 NPs transforms from saturable absorption to reverse-saturable absorption. However, NWs and NWAs exhibit the opposite change. At 780nm, all samples show reverse-saturable absorption, but have different sensitivities to excitation intensity. Due to the larger surface-to-volume ratio of NPs and less defects of NWAs by annealing, nonlinear optical absorption coet^icients follow the order NPs≥ NWs≥ NWAs. The results also show that these shape and annealing effects axe dominant at low excitation intensity, but do not exhibit at the high excitation intensity. The NLO refractive index of NPs shows a positive linear relationship with the excitation intensity, whereas NW and NWAs exhibit a negative linear relationship. The results could provide some foundational guidance to applications of anatase TiO2 in optoelectronic devices or other aspects. 展开更多
关键词 NP Dependence of Nonlinear Optical Response of Anatase TiO2 on Shape and excitation intensity NLO TiO
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Response of train-bridge system under intensive seismic excitation by random vibration method 被引量:2
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作者 WU Zhao-zhi ZHANG Nan 《Journal of Central South University》 SCIE EI CAS CSCD 2022年第8期2467-2484,共18页
Earthquake is a kind of sudden and destructive random excitation in nature.It is significant to determine the probability distribution characteristics of the corresponding dynamic indicators to ensure the safety and t... Earthquake is a kind of sudden and destructive random excitation in nature.It is significant to determine the probability distribution characteristics of the corresponding dynamic indicators to ensure the safety and the stability of structures when the intensive seismic excitation,the intensity of which is larger than 7,acts in train-bridge system.Firstly,the motion equations of a two-dimensional train-bridge system under the vertical random excitation of track irregularity and the vertical seismic acceleration are established,where the train subsystem is composed of 8 mutually independent vehicle elements with 48 degrees of freedom,while the single-span simple supported bridge subsystem is composed of 102D beam elements with 20 degrees of freedom on beam and 2 large mass degrees of freedom at the support.Secondly,Monte Carlo method and pseudo excitation method are adopted to analyze the statistical parameters of the system.The power spectrum density of random excitation is used to define a series of non-stationary pseudo excitation in pseudo excitation method and the trigonometric series of random vibration history samples in Monte Carlo method,respectively solved by precise integral method and Newmark-βmethod through the inter-system iterative procedure.Finally,the results are compared with the case under the weak seismic excitation,and show that the samples of vertical acceleration response of bridge and the offload factor of train obeys the normal distribution.In a high probability,the intensive earthquakes pose a greater threat to the safety and stability of bridges and trains than the weak ones. 展开更多
关键词 random vibration method intensive seismic excitation train-bridge system probability distribution inter system iteration precise integral method
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REDUCING RF EXCITE PULSE INTENSITY TO IMPROVE MRI IMAGE QUALITY IN SOME OF COILS
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《Chinese Journal of Biomedical Engineering(English Edition)》 1999年第4期89-90,共2页
关键词 MRI RF REDUCING RF EXCITE PULSE intensity TO IMPROVE MRI IMAGE QUALITY IN SOME OF COILS
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What are Exciting in Laser Science
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作者 Yuen Ron Shen Department of Physics, University of California Materials Sciences Division Lawrence Berkeley National Laboratory Berkeley, CA 94720, USA 《Tsinghua Science and Technology》 SCIE EI CAS 1998年第1期14-26,共13页
Recent advances in selected areas of laser science are briefly reviewed. They include laser technology, coherent control of quantum systems by lasers, X ray generation by ultrashort high intensity laser pulses, and ... Recent advances in selected areas of laser science are briefly reviewed. They include laser technology, coherent control of quantum systems by lasers, X ray generation by ultrashort high intensity laser pulses, and laser spectroscopic studies of surface catalysis in real environment. 展开更多
关键词 laser science coherent control coherent excitation dark state laser technology tunable lasers X ray generation femtosecond pulses high intensity laser excitation high order harmonic generation surface nonlinear optical spectroscopy surface c
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Enhancement of 2.0 μm fluorescence emission in new Ho^(3+)/Tm^(3+)/Yb^(3+) tri-doped tellurite glasses
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作者 程盼 杨风景 +3 位作者 周自忠 黄波 吴立波 周亚训 《Optoelectronics Letters》 EI 2016年第5期340-343,共4页
For enhancing the 2.0 μm band fluorescence of Ho^(3+), a certain amount of WO_3 oxide was introduced into Ho^(3+)/Tm^(3+)/Yb^(3+) tri-doped tellurite glass prepared using melt-quenching technique. The prepared tri-do... For enhancing the 2.0 μm band fluorescence of Ho^(3+), a certain amount of WO_3 oxide was introduced into Ho^(3+)/Tm^(3+)/Yb^(3+) tri-doped tellurite glass prepared using melt-quenching technique. The prepared tri-doped tellurite glass was characterized by the absorption spectra, fluorescence emission and Raman scattering spectra, together with the stimulated absorption, emission cross-sections and gain coefficient. The research results show that the introduction of WO_3 oxide can further improve the 2.0 μm band fluorescence emission through the enhanced phonon-assisted energy transfers between Ho^(3+)/Tm^(3+)/Yb^(3+) ions under the excitation of 980 nm laser diode(LD). Meanwhile, the maximum gain coefficient of Ho^(3+) at 2.0 μm band reaches about 2.36 cm^(-1). An intense 2.0 μm fluorescence emission can be realized. 展开更多
关键词 glasses Tm Yb phonon excitation quenching reaches sections intense realized
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