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151.
Perovskite-type lithium fast ion conductors of Li3xLa0.67−xScyTi1−2yNbyO3 system were prepared by solid state reaction. X-Ray powder diffraction shows that perovskite solid solution form in the ranges
of x=0.10, y≤0.10. AC impedance measurements indicate that the bulk conductivities and the total conductivities are of the
order of 10−4 S·cm−1 and 10−5 S·cm−1 at 25 °C respectively. The compositions have low bulk activation energies of about 17 kJ/mol in the temperature ranges of
298 – 523 K and total activation energies of about 37 kJ/mol in the temperature ranges of 298 – 523 K. 相似文献
152.
153.
This paper investigates mutual influence of duct and room acoustics in the whole fan-duct-plenum-room integrations. Applying the parametric design language of finite element software ANSYS (APDL), dimensional and positional influence on system acoustics has been studied. Models with different room dimensions, duct lengths, duct cross-sections, duct locations, duct discharges and duct elbow were constructed, and their characteristics were compared qualitatively. Results show that small rooms, short ducts, large duct cross-sections and bell mouth duct discharges help to increase room sound pressure levels (SPLs); SPLs in ducts and plenums are sensitive to duct dimensions and duct discharge types but insensitive to duct locations and room dimensions; duct elbows have relatively indistinct acoustic influence in each component. Based on the calculation results, a semi-experimental method was proposed for simply and approximately evaluating indoor acoustic spectra of fan-duct-plenum-room integrations, then an example was used to demonstrate the prediction process. Finally, by adopting several ideal models, sound field constitutions, duct and room wall admittances and duct end reflection were explored quantitatively. This study may give a detailed understanding of fan-duct-plenum-room acoustics for researchers, also it might provide a new, simple and approximate prediction method for professionals to evaluate and improve fan-ducted acoustics. 相似文献
154.
Jie Xue Liang Chen Li Zhou Zhifeng Jia Yanping Wang Xinyuan Zhu Deyue Yan 《Journal of Polymer Science.Polymer Physics》2006,44(15):2050-2057
α‐Cyclodextrin (α‐CD) has been complexed with various poly(ethylene glycol) (PEG) derivatives in aqueous solution. It has been found that the end groups of PEG derivatives affect the complexation kinetics greatly, but have only a little influence on the thermodynamic behavior. By increasing the hydrophobicity of end groups, the complexation speeds up rapidly. On the other hand, the bulky end groups slow down the threading of polymeric guests into the cavity of CD. By changing the hydrophobicity and the size of end groups, the complexation rate can be adjusted in the range of several orders of magnitudes, which should be quite useful in the design of new supramolecular systems. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2050–2057, 2006 相似文献
155.
新疆野生黑加仑与马林果实的营养成分分析 总被引:2,自引:0,他引:2
通过对新疆野生黑加仑和野生马林的脂肪油,8种微量元素,17种氨基酸以及维生素C的含量进行测定得出:黑加仑脂肪油含量为17.9%,马林的脂肪油含量为22.3%,其中,黑加仑脂肪油中,r-亚麻酸的含量为19.02%,而马林中,其含量为9.40%,黑加仑中K,Na,Ca,Cu,Zn,Fe的含量比马林中的含量高,而Mn,Mg元素的含量却比马林含量低;马林的维生素C含量为16.22mg/g,黑加仑的含量为108mg/g,黑加仑的氨基酸的总量为1.63%,马林为1.14%。 相似文献
156.
Ying Zhang Gang Hu Shigang Chen H.A. Cerdeira 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,27(3):381-384
A method of controlling global stochasticity in Hamiltonian systems by applying nonlinear perturbation is proposed. With the
well-known standard map we demonstrate that this control method can convert global stochasticity into regular motion in a
wide chaotic region for arbitrary initial condition, in which the control signal remains very weak after a few kicks. The
system in which chaos has been controlled approximates to the original Hamiltonian system, and this approach appears robust
against small external noise. The mechanism underlying this high control efficiency is intuitively explained.
Received 15 January 2002 Published online 6 June 2002 相似文献
157.
Chai-Chin Lin Chih-Ming Chen Jenn-Hwan Tarng Hsueh-Ming Hang Hsiao-Cheng Yu 《Broadcasting, IEEE Transactions on》2002,48(1):38-43
Field tests of the transmission performance of the ATSC DTV system have been conducted in Taiwan. The test results as well as comparisons against the NTSC system performance are reported and analyzed. From the measured results the reception characteristics of the DTV can be deduced and can provide guidelines for television stations to design the transmission system, schedule equipment deployment, plan service coverage areas, and improve the reception quality of the digital signal 相似文献
158.
以TD—SCDMA既有进展及面临的挑战与NGBWM的发展走向为基础,重点论述自主创新导向下的TD—SCDMA与NGBWM务实发展战略思考。 相似文献
159.
Chen J.J. Gao G.-B. Chyi J.-I. Morkoc H. 《Electron Devices, IEEE Transactions on》1989,36(10):2165-2172
Avalanche breakdown behavior at the collector junction of the GaAs/AlGaAs HBT (heterojunction bipolar transistor) has been studied. Junction breakdown characteristics displaying hard breakdown, soft breakdown, and negative resistance breakdown behavior were observed and are interpreted by analysis of localized microplasma effects, uniform microplasma-free behavior, and associated current gain measurements. Light emission from the collector-base junction of the GaAs/AlGaAs HBT was observed and used to investigate breakdown uniformity. Using a simple punchthrough breakdown model, the theoretical breakdown curves at different collector doping concentrations and thicknesses were computed and found to be in agreement with maximum breakdown voltages measured from devices displaying the most uniform junction breakdown. The serious current gain degradation of GaAs/AlGaAs HBTs at low current densities was analyzed in connection with the measurement of a large collector-emitter breakdown voltage. The unexpected functional relationship between the collector-emitter breakdown voltage and collector-base breakdown voltage is explained by the absence of a hole-feedback effect for devices not exhibiting transistor action 相似文献
160.
We have prepared composite magnetic core–shell particles using the process of soap-free emulsion polymerization and the co-precipitation method. The shell of the synthesized composite sphere is cobalt ferrite (CoFe2O4) nanoparticles and the core consists of poly(styrene-co-methacrylic acid) polymer. The mean crystallite sizes of the coated CoFe2O4 nanoparticles were controlled in the range of 2.4–6.7 nm by the concentration of [NH4+] and heated temperature. The magnetic properties of the core–shell spherical particles can go from superparamagnetic to ferromagnetic behavior depending on the crystalline sizes of CoFe2O4. 相似文献