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141.
沈园云 《上海轻工业高等专科学校学报》2010,(1):52-54
通过对SEL-351A的零(负)序方向元件分别在接地方向、相间故障方向及三相短路故障方向的理论分析,结合电测试数据阐述了对SEL-351A继电器方向元件的认识。 相似文献
142.
根据研究区56口井,笔者对岩心、自然伽马、自然电位、声波时差、密度、中子等钻井、测井资料进行多种统计和交会分析,研究速度、密度、波阻抗、孔隙度与深度、岩性,波阻抗与孔隙度等的关系,分析储层物性特征,并作相关交会图,建立规律关系式。经比较得出利用波阻抗进行下一步的反演工作会比较合理。根据砂岩孔隙度与波阻抗之间的函数关系,可以利用砂岩波阻抗估算砂岩孔隙度。为下一步储层预测研究提供良好的基础资料。 相似文献
143.
XU Bin WU ZhenSen WU Jian & XUE Kun School of Science Xidian University Xi’an China State Key Laboratory of Electromagnetic Environment China Research Institute of Radiowave Propagation Beijing 《中国科学E辑(英文版)》2009,52(4):1112-1116
The electron velocity distribution function and the incoherent scatter spectra during ionospheric heating in low ionosphere
region are presented with consideration of the elastic collision between electrons and neural particles and the excitation
of rotation energy level. The effects of pump frequency and electric fields on the spectra are discussed. With the increase
of electric field, the non-Maxwellian feature is enhanced, and with the increase of heating frequency, the non-Maxwellian
feature is weakened. The non-Maxwellian factor will bring a large error in ionosphere parameters, which must be considered
in the inversion.
Supported by the National Natural Science Foundation of China (Grant No. 40310223), the National Key Laboratory of Electromagnetic
Environment (LEME), and National Key Technologies R&D Program of China (Grant No. 2006BAB18B06) 相似文献
144.
Multi-channel micro neural probe fabricated with SOI 总被引:1,自引:0,他引:1
WeiHua Pei Lin Zhu ShuJing Wang Kai Guo Jun Tang Xu Zhang Lin Lu ShangKai Gao HongDa Chen 《中国科学E辑(英文版)》2009,52(5):1187-1190
Silicon-on-insulator(SOI) substrate is widely used in micro-electro-mechanical systems(MEMS).With the buried oxide layer of SOI acting as an etching stop,silicon based micro neural probe can be fabri-cated with improved uniformity and manufacturability.A seven-record-site neural probe was formed by inductive-coupled plasma(ICP) dry etching of an SOI substrate.The thickness of the probe is 15 μm.The shaft of the probe has dimensions of 3 mm×100 μm×15 μm with typical area of the record site of 78.5 μm2.The im... 相似文献
145.
电磁流量计输出的流速信号非常微弱,且常叠加共模干扰,经信号调理电路放大后,会导致信噪比很低,甚至淹没有用信号.针对这问题提出了利用前置放大电路有效抑制共模干扰,对其进行定性、定量分析,给出实际可行的提高差动放大电路输入阻抗的设计,并进行分析、推导和对比计算,证明其可以很大限度抑制共模干扰,提高测量准确度. 相似文献
146.
147.
The use of electrochemically synthesized polyindole (PIN) film was investigated for protective coating on 304-stainless steel (SS). Polyindole was deposited via anodic oxidation of the corresponding monomer, indole in acetonitrile (ACN) solution containing LiClO4. It provided an adherent and stable coating on SS. The corrosion performance of coated and uncoated SS was investigated in 3.5% NaCl solution using electrochemical impedance spectroscopy (EIS), anodic polarization curves and open-circuit potential–time (Eocp–t) diagrams. These tests demonstrated that PIN coating provided important barrier effect to SS for important immersion times in aggressive medium. 相似文献
148.
149.
AgPb2B2V3O12 (B = Mg, Zn) ceramics with low sintering temperature were synthesized via the conventional solid-state reaction route. Rietveld refinements of the X-ray diffraction patterns confirm cubic symmetry with space group . The number of observed vibrational modes and those predicted by group theoretical calculations also confirm the space group. At the optimum sintering temperature of 750°C/4 hours, AgPb2Mg2V3O12 has a relative permittivity of 23.3 ± 0.2, unloaded quality factor () of 26 900 ± 500 GHz (), and temperature coefficient of resonant frequency of 19.3 ± 1 ppm/°C, while AgPb2Zn2V3O12 has the corresponding values of 26.4 ± 0.2, 28 400 ± 500 GHz () and –18.4 ± 1 ppm/°C at 590°C/4 hours. Microwave dielectric properties of a few reported garnets and Pb2AgB2V3O12 (B = Mg, Zn) ceramics were correlated with their intrinsic characteristics such as the Raman shifts as well as width of A1g Raman bands. Higher quality factor was obtained for lower full width at half-maxima (FWHMs) values of A1g modes. The increase in B-site bond valence contributes to high and low |τf| with the substitution of Zn2+ by Mg2+. Furthermore, the high ionic polarizability and unit cell volume with Zn2+substitution contribute to increased relative permittivity. 相似文献
150.
The use of electrochemical noise methods (ENM) to study thick, high impedance coatings 总被引:2,自引:0,他引:2
Gordon P. Bierwagen Carol S. Jeffcoate Junping Li S va Balbyshev Dennis E. Tallman Douglas J. Mills 《Progress in Organic Coatings》1996,29(1-4):21-29
Thick, high impedance organic coatings are those class of coatings used to provide corrosion protection to naval vessels, pipelines, gasoline storage tanks, and other large structures such as bridges and plant structures. These coatings, especially the newest generations now being used in practice, can provide exceptional protection and lifetime of performance such that properly and accurately assessing and differentiating among competing coatings is a very difficult task. The standard protocol of salt fog testing (ASTM B117), immersion testing, and outdoor exposure in a corrosive environment with subjective evaluation of a coating's performance durings and after testing, does not adequatcly rank and predict coating lifetimes for new coating systems, especially for the environmentally compliant coating systems such as powder coatings (especially the thick, fusion bonded epoxy (FBE) coatings used for pipelines), two component epoxy and urethane coatings and waterborne coatings. New, objective test methods are desperately needed by users and manufacturers of coatings. A relatively new electrochemical test procedure, electrochemical noise methods (ENM), as developed by Skerry and Eden, has been shown in our laboratory to be very successful in the ranking and prediction of relative coating performance. We have used the method successfully on naval ship coatings, several pipeline coatings and other related systems, and Skerry has used them successfully on industrial maintenance coatings. We have used these methods in conjunction with electrochemical impedance spectroscopy, d.c. resistance measurements and cyclic salt fog testing of the ProhesionTM type. In our studies of pipeline coatings, we needed to investigate thermal effects because of their extended range of use temperature. In these studies, we have discovered that electrochemical methods can be used for an in situ measurement of the Tg of coatings in electrolyte immersion. Further, the ‘plasticizing’ effect of aqueous electrolyte absorption as well as its relative irreversibility has been shown. For all coatings studied, ENM provided useful, objective, numerical data which rapidly ranks coatings and provides useful information on the relative lifetime prediction of coatings which may provide up to 30 years of service. 相似文献