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91.
针对输电线路测量中,不能直接精确测定钢管杆中心坐标的问题。提出了使用三距离交会的测量方法,以及利用网络RTK配合手持电子测距仪,快速测得钢管杆附近三个点的坐标以及相应距离。针对不同观测数据编写了相应的VB程序,提高了工作效率。 相似文献
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94.
Kenneth T. Leong James C. Booth J. H. Claassen 《Journal of Superconductivity and Novel Magnetism》2006,19(7-8):637-648
We introduce a novel transmission-line method for determining the penetration depth in thin high-temperature superconducting
(HTS) films. The method is based on the accurate measurement of the inductance per unit length of a superconducting coplanar-waveguide
(CPW) transmission line fabricated on the HTS sample. Using the experimentally obtained inductance per unit length, we interpolate
the penetration depth from a table of numerically determined values of inductance (per unit length) as a function of penetration
depth, calculated from a coupled transmission-line model. A novelty of our procedure is the utilization of the multiline thru-reflect-line
(TRL) method and the calibration-comparison method to accurately determine the inductance per unit length of the superconducting
transmission line. By measuring different CPW geometries patterned onto the same thin-film sample, we can verify our penetration
depth values. We demonstrate this technique by extracting the penetration depth for several different HTS films at 76 K. Estimated
uncertainties in the extracted penetration depth are also provided.
Contribution of an agency of the US government not subject to copyright. 相似文献
95.
Nanocluster beam technology combined with conventional sputtering was used to fabricate FePt–SiO2 nanocomposite films in this present work. The post-deposition annealing affected the final particle size and size distribution of FePt nanoclusters. The effects of both volume fraction of SiO2 matrix and annealing temperature on magnetic and microstructural properties were studied. Partial ordering, grain growth and agglomeration of FePt particles in FePt–SiO2 nanocomposite films occurred during annealing. A higher volume fraction of SiO2 matrix was effective in suppressing diffusion of atoms and magnetic exchange coupling of FePt grains. Excessive SiO2 however resulted in a lower degree of FePt ordering and thus lower coercivity. 相似文献
96.
基于同步相量测量技术的广域测量系统为电力系统各领域中新应用功能的研究开发提供了全新的数据支撑平台。文章简要介绍了同步相量测量技术及在此基础之上的广域测量系统的发展现状;着重分析了PMU量测数据在包括阻尼控制、暂稳分析及控制、电压稳定、解列控制在内的电力系统动态领域以及包括线路参数测量、状态估计、潮流计算在内的电力系统稳态领域和继电保护领域中的应用研究情况;同时对这些应用研究的特点、优点以及存在的主要问题进行了相应的评述。 相似文献
97.
Y. Gomeniuk A. Nazarov Ya. Vovk Yi Lu O. Buiu S. Hall J.K. Efavi M.C. Lemme 《Materials Science in Semiconductor Processing》2006,9(6):980
Metal-oxide-semiconductor capacitors based on HfO2 gate stack with different metal and metal compound gates (Al, TiN, NiSi and NiAlN) are compared to study the effect of the gate electrode material on the trap density at the insulator–semiconductor interface.C–V and G–ω measurements were made in the frequency range from 1 kHz to 1 MHz in the temperature range 180–300 K. From the maximum of the plot G/ω vs. ln(ω) the density of interface states was calculated, and from its position on the frequency axis the trap cross-section was found. Reducing temperature makes it possible to decrease leakage current through the dielectric and to investigate the states located closer to the band edge.The structures under study were shown to contain significant interface trap densities located near the valence band edge (around 2×1011 cm−2eV−1 for Al and up to (3.5–5.5)×1012 cm−2 eV−1 for other gate materials). The peak in the surface state distribution is situated at 0.18 eV above the valence band edge for Al electrode. The capture cross-section is 5.8×10−17 cm2 at 200 K for Al–HfO2–Si structure. 相似文献
98.
M.V.V.M. Satya Kishore 《Materials Research Bulletin》2005,40(10):1705-1712
LiCo1−xMxPO4 (M = Mg2+, Mn2+ and Ni2+; 0 ≤ x ≤ 0.2) compounds have been synthesized by solid-state reaction method and studied as cathode materials for secondary lithium batteries. LiCoPO4 exhibits a discharge plateau at ∼4.7 V with an initial discharge capacity of 125 mAh/g and on cycling capacity falls. Substitution of Co2+ with Mg2+/Mn2+/Ni2+ in LiCoPO4 has an influence on the initial discharge capacity and on cycling behaviour. The capacity retention of LiCoPO4 is improved by manganese substitution. Among the manganese substituted phases, LiCo0.95Mn0.05PO4 shows good reversible capacity of ∼50 mAh/g. 相似文献
99.
In this work the problem of designing a state estimator for completely or partially observable continuous nonlinear plants with discrete measurements is addressed. The combination of a geometric approach with a stability analysis yields an estimator design methodology with a nonlinear detectability condition susceptible of testing, a systematic estimator construction, a robust convergence criterion coupled with a simple tuning scheme, as well as a rationale to explain the interplay between sampling time, estimator gains, and estimator functioning. Comparing with the continuous measurement case where the convergence is attained by tuning the gain above a low limit, in the discrete measurement case the loss of information due to the measurement sampling increases the size of the lower gain limit, and imposes sampling time and high gain limits. The proposed methodology is applied to address the estimation problem of a class of solution homopolymerization reactors, and is tested with a methyl-methacrylate polymerization run taken from a previous extended Kalman filter implementation study with experimental data. 相似文献
100.
Shengyuan Xu Author Vitae Author Vitae 《Automatica》2003,39(3):509-516
This paper is concerned with the problem of robust H∞ filtering for uncertain impulsive stochastic systems under sampled measurements. The parameter uncertainties are assumed to be time-varying norm-bounded. The aim is to design a stochastically stable filter, using the locally sampled measurements, which ensures both the robust stochastic stability and a prescribed level of H∞ performance for the filtering error dynamics for all admissible uncertainties. A sufficient condition for the existence of such a filter is proposed in terms of certain linear matrix inequalities (LMIs). When these LMIs are feasible, an explicit expression of a desired filter is given. An example is provided to demonstrate the effectiveness of the proposed approach. 相似文献