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961.
Abu-Zayyad T Belov K Bird DJ Boyer J Cao Z Catanese M Chen GF Clay RW Covault CE Cronin JW Dai HY Dawson BR Elbert JW Fick BE Fortson LF Fowler JW Gibbs KG Glasmacher MA Green KD Ho Y Huang A Jui CC Kidd MJ Kieda DB Knapp BC Ko S 《Physical review letters》2000,84(19):4276-4279
The average mass composition of cosmic rays with primary energies between 10(17) and 10(18) eV has been studied using a hybrid detector consisting of the High Resolution Fly's Eye (HiRes) prototype and the MIA muon array. Measurements have been made of the change in the depth of shower maximum and the muon density as a function of energy. The results show that the composition is changing from a heavy to lighter mix as the energy increases. 相似文献
962.
分析了当前学生缺乏提出问题能力的原因,从教师的教学实际出发,借鉴成功教育的理念,通过培养学生在探究学习中敢问、能问,直到学生会问,逐步提高学生的学习、探究和创新的能力. 相似文献
963.
964.
纳米材料用于吸收电磁波的物理机制 总被引:1,自引:0,他引:1
本文从物理学的角度分析吸波材料与电磁波作用的影响因素和纳米材料在吸波应用上的微观机制,随着纳米材料和纳米科技的深入发展,纳米吸波材料将以更优异的性能广泛应用于军事装备和民用电磁波防护上. 相似文献
965.
In this paper, the adaptive synchronization and lag synchronization are considered for uncertain dynamical system with time delay based on parameter identification and a novel control method is then further given using the Lyapunov functional method. With this new and effective method, parameter identification and lag synchronization can be achieved simultaneously. Simulation results are given to justify the theoretical analysis in this paper. 相似文献
966.
Jiagang Wu Dingquan Xiao Jiliang Zhu Jianguo Zhu Junzhe Tan 《Applied Surface Science》2007,253(20):8365-8370
The (Pb0.90La0.10)Ti0.975O3/PbTiO3 (PLT/PT), PbTiO3/(Pb0.90La0.10)Ti0.975O3/PbTiO3 (PT/PLT/PT) multilayered thin films with a PbOx buffer layer were in situ deposited by RF magnetron sputtering at the substrate temperature of 600 °C. With this method, highly (1 0 0)-oriented PLT/PT and PT/PLT/PT multilayered thin films were obtained. The PbOx buffer layer leads to the (1 0 0) orientation of the films. The dielectric, ferroelectric and pyroelectric properties of the PLT multilayered thin films were investigated. It is found that highly (1 0 0)-oriented PT/PLT/PT multilayered thin films possess higher remnant polarization 2Pr (44.1 μC/cm2) and better pyroelectric coefficient at room temperature p (p = 2.425 × 10−8 C/cm2 K) than these of PLT and PLT/PT thin films. These results indicate that the design of the PT/PLT/PT multilayered thin films with a PbOx buffer layer should be an effective way to enhance the dielectric, ferroelectric and pyroelectric properties. The mechanism of the enhanced ferroelectric properties was also discussed. 相似文献
967.
968.
Dunxi Yu Minghou Xu Hong Yao Jiancai Sui Xiaowei Liu Yun Yu Qian Cao 《Proceedings of the Combustion Institute》2007,31(2):1921-1928
The chemical composition of particles generated during pulverized coal combustion is the consequence of their formation processes. This work aims to use the size resolved elemental composition of coal-derived particles to identify their formation modes. A size-classified bituminous coal is burnt in a laboratory drop tube furnace at 1150, 1250, and 1350 °C, respectively. The elemental composition of the size-segregated particles from coal combustion is analyzed and the total mass fraction size distributions of Si and Al are obtained. Three particle formation modes are observed in these distribution profiles. The coarse mode has the highest value of the total mass fraction of Si and Al while the ultrafine mode has the lowest one. The total mass fraction of Si and Al in these two modes is nearly independent of particle size. It is believed that the coarse mode is formed by the mineral coalescence mechanism and the ultrafine mode by the vaporization–condensation mechanism. The difference in the total mass fraction of Si and Al between the central mode and the other two indicates that the central mode is formed by different mechanisms. Based on the observation that the total mass fraction of Si and Al in this mode increases with increasing particle size, heterogeneous condensation of vaporized species on existing fine residual ash particles is proposed to account for the formation of these particles. The study of the elemental composition of the three modes represented in five categories verifies the proposed formation mechanisms for them to some extent. 相似文献
969.
Efficient polymer white-light-emitting diodes (WPLEDs) have been fabricated with a single layer of fluorescent polymer blend. The device structure consists of ITO/PEDOT/PVK/emissive layer/Ba/Al. The emissive layer is a blend of poly(9,9-dioctylfluorene) (PFO), phenyl-substituted PPV derivative (P-PPV) and a copolymer of 9,9-dioctylfluorene and 4,7-di(4-hexylthien-2-yl)-2,1,3-benzothiadiazole (PFO-DHTBT), which, respectively, emits blue, green and red light. The emission of pure and efficient white light was implemented by tuning the blend weight ratio of PFO: P-PPV: PFO-DHTBT to 96:4:0.4. The maximum current efficiency and luminance are, respectively, 7.6 cd/A at 6.7 V and 11930 cd/m2 at 11.2 V. The CIE coordinates of white-light emission were stable with the drive voltages. 相似文献
970.