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41.
Peng Gao Cheng-chang Jia Wen-bin Cao Cong-cong Wang Dong Liang Guo-liang Xu 《矿物冶金与材料学报》2014,21(6):589-594
In this study, we have investigated how the dielectric loss tangent and permittivity of AlN ceramics are affected by factors such as powder mixing methods, milling time, sintering temperature, and the addition of a second conductive phase. All ceramic samples were prepared by spark plasma sintering (SPS) under a pressure of 30 MPa. AlN composite ceramics sintered with 30wt%–40wt% SiC at 1600℃ for 5 min exhibited the best dielectric loss tangent, which is greater than 0.3. In addition to AlN and β-SiC, the samples also contained 2H-SiC and Fe5Si3, as detected by X-ray difraction (XRD). The relative densities of the sintered ceramics were higher than 93%. Experimental results indicate that nano-SiC has a strong capability of absorbing electromagnetic waves. The dielectric constant and dielectric loss of AlN-SiC ceramics with the same content of SiC decreased as the frequency of electromagnetic waves increased from 1 kHz to 1 MHz. 相似文献
42.
移动互联网和物联网的发展带来数据业务的蓬勃发展,对移动系统带宽需求激增,促使运营商大力发展面向数据业务的LTE技术,特别是采用非对称频谱的TD-LTE技术。本文分析TD-LTE系统组网应考虑的内容,研究TD-LTE系统本身及与TD-SCDMA系统进行同频组网的可行性,给出面向数据业务的TD-LTE系统组网总体建议。 相似文献
43.
The NONEL high precision MS Delay Detonator (FDG-1detonator) is introduced. The main aspects about the FDG-1 detonator include the choice of structure, delay composition, control of the gas chamber, optimum charge and density, suitable explosives per meter in the NONEL tube, base firing charge and the main specifications. The improvement of the characteristics of FDG-1 detonator has been tested systematically. The testing method is reliable and its precision can meet the demand for usage. 相似文献
44.
The lower slope of furrow pits has following special features: small extent of weathering destruction, short time of production blasting damage, good arching effect of lower slope with small curvature radius, and good bottom effect of a pit end for transferring and bearing initial horizontal stresses in lower slope. The new principles provided theoretical basis for convex slope in furrow pits to reduce stripping. Similar phenomena and examples are supplied simultaneously. 相似文献
45.
Some studies have shown that native Chinese speakers have different laterality in matched Stroop tasks from native English speakers. Recently, many imaging data, which show left laterality of English-matched Stroop interference, have been reported. And a few functional imaging studies have been conducted to investigate the phenomenon of the Chinese version of Stroop task. In this study, functional activity in the lateral prefrontal cortex of a group of normal Chinese boys with functional near-infrared imaging during a Stroop color-word task was measured to show different Stroop interferences in the prefrontal cortex. The results show obvious fluctuation of the cerebral blood volume in the right prefrontal cortex in all boys, which agrees with the finding of previous studies, that is, Chinese native boys have right laterality in their brain when the Chinese version of Stroop color-word task is applied. 相似文献
46.
Peng Funan 《中国工程科学》2008,6(2):9-18
The success of the prediction of Haicheng earthquake and the failure of the prediction of Tangshan earthquake were both well known in the world. What happened, why such a strong earthquake as occurred in Haicheng had been predicted successfully and with a small loss of lives and property? Why a successively strong earthquake about a year later in a region not so further was failure in the imminent stage of prediction and there were so many fatalities and a great degree of property? The author addresses these points based on these true experiences including the first hand experiences leading up to, during, and following these two earthquarter. In addition, he also introduced some seimic phenomena which he had seen after Chi-chi earthquake in Taiwan. 相似文献
47.
48.
DING Bin WANG Hongmei YI Long CHENG Peng LI Licun ZHAI Yuping LIAO Daizheng YAN Shiping & JIANG Zonghui Department of Chemistry Nankai University Tianjin China Correspondence should be addressed to Cheng Peng or Liao Daizheng 《科学通报(英文版)》2003,48(22):2446-2449
Spin-crossover complexes are of great interest to the scientists because of their potential application in molecular-based electronic devices. Some octahedral metal compounds with 3dn (4 ≤ n ≤ 7) configuration can induce a spin state conversion through a fine tuning condition (temperature, pressure, light irradiation, etc.). If the conversion occurs reversibly with a hystersis loop and color change, it will make the system possessing memory effect. The memory effect can be magnified and the … 相似文献
49.
Referring to research on the Heterogeneous Network(Het-Net) application scenario and technique characters in IMT-Advanced(The 4th Generation Mobile Communications) cellular system,this paper provides further analysis on main technique aspects of Heterogeneous Network,discussion on interference issue due to multi-layer building by access points and their corresponding solutions from standardization and engineering implementation. The proposed solution can effectively solve the interference problem in IMT-advanced Het-Net,and also improves the networking performance dramatically for future mobile communication systems. 相似文献
50.
Some studies have shown that native Chinese speakers have different laterality in matched Stroop tasks from native English speakers.Recently,many imaging data,which show left laterality of English-matched Stroop interference,have been reported.And a few functional imaging studies have been conducted to investigate the phenomenon of the Chinese version of Stroop task.In this study,functional activity in the lateral prefrontal cortex of a group of normal Chinese boys with functional near-infrared imaging during a Stroop color-word task was measured to show different Stroop interferences in the prefrontal cortex.The results show obvious fluctuation of the cerebral blood volume in the right prefrontal cortex in all boys,which agrees with the finding of previous studies,that is,Chinese native boys have right laterality in their brain when the Chinese version of Stroop color-word task is applied. 相似文献