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921.
Novel Broadband Reflectarray Antenna with Windmill-Shaped Elements for Millimeter-Wave Application 总被引:1,自引:0,他引:1
Hua Li Bing-Zhong Wang Ping Du 《International Journal of Infrared and Millimeter Waves》2007,28(5):339-344
A novel broadband millimeter-wave reflectarray antenna composed of windmill-shaped elements of variable lengths is proposed.
Compared to the conventional single-layer reflectarray elements, the windmill-shaped elements can realize much larger phase
variation range (over 600°), leading to broader bandwidth. Using this technique, a 15°-beam-steering reflectarray operating
at 30 GHz is designed. The computed results demonstrate the agreement of the main beam steering with the design requirement,
and a 1-dB gain bandwidth close to 20% is obtained. The validity of the obtained results is verified by comparing the ones
generated by Ansoft High Frequency Structure Simulator (HFSS) with those produced by Ansoft Designer. The antenna is useful
for millimeter-wave applications.
This work was supported by the National Natural Science Foundation of China (No. 90505001), the High-Tech Research and Development
Program of China (No. 2006AA01Z275), and the Creative Research Group Program of UESTC. 相似文献
922.
模块性(modularity)是度量网络社区结构(community structure)的主要参数.探讨了Watts和Strogatz的小世界网络(简称W-S模型)以及Barabàsi 等的B-A无标度网络(简称B-A模型)两类典型复杂网络模块性特点.结果显示,网络模块性受到网络连接稀疏的影响,W-S模型具有显著的社区结构,而B-A模型的社区结构特征不明显.因此,应用中应该分别讨论网络的小世界现象和无标度特性.社区结构不同于小世界现象和无标度特性,并可以利用模块性区别网络类型,因此网络复杂性指标应该包括
关键词:
模块性
社区结构
小世界网络
无标度网络 相似文献
923.
924.
为了实现在石油工业地质研究中用先进的网络系统管理前磁信息数据,使用面向Agent的软件工程方法——Gaia方法详细分析了油田前磁信息数字化信息管理系统,建立了该系统的分析模型和设计模型,将Gaia和OAA的系统分析与设计方法应用在基于Multi Agent前磁信息处理系统中.本文应用Gaia的分析方法建立了系统的角色模型,在此基础上构建了基于Multi Agent前磁信息数据处理整体框架体系,该体系也可基于异构平台的数据环境. 相似文献
925.
DU JinFeng LI Ying ZHANG Qi YAO XiaoJun 《科学通报(英文版)》2007,52(2):200-204
The presence of several high affinity binding sites on human serum albumin (HSA) makes it a possible target for many drugs. This study is designed to examine the effect of aloe-emodin on HSA by fluo-rescence, CD spectroscopy and molecular modeling. The results of fluorescence measurements sug-gested that the hydrophobic interaction was the predominant intermolecular force stabilizing the AE-HSA complex, which was in good agreement with the result of molecular modeling study. And the enthalpy change ΔH0 and the entropy change ΔS0 were calculated to be -7.041 kJ·mol-1 and 76.619 J·mol-1·K-1 according to the Van't Hoff equation. The alterations of protein secondary structure in the presence of AE in aqueous solution were quantitatively calculated from CD spectra, and the content of α-helices obviously increased. 相似文献
926.
DU Lin XU YongFu GE MaoFa JIA Long YAO Li 《科学通报(英文版)》2007,52(12):1629-1634
Large quantities of di-tert-butyl peroxide (DTBP) have been emitted into the troposphere due to human activities. Its role in the atmospheric photochemical reaction has not been understood. This study presents the results of the photochemical reactions of DTBP and NOx, which have been simulated in a self-made smog chamber under the temperature of (29±1)℃. Both the wall decays of ozone and NO2 could be neglected, compared to the results in simulative experiments. The effective intensity of UV light used in the experiments was 1.28×10-3 s-1, which was expressed by the rate constant of NO2 photolysis in purified air. The reaction mechanism was proposed according to our results and reports of other researchers. The maximum values of incremental reactivity (IR) in the three simulative ex- periments were 9.53×10-2, 5.23×10-2 and 3.78×10-2, respectively. The incremental reactivity decreased with the increase of initial concentrations of DTBP. The IR value of DTBP obtained in this study was comparable to that of acetylene reported in our previous research. 相似文献
927.
本文主要通过Win32汇编语言编写的一个窗口程序,解释了Windows操作系统的多任务结构和它的消息处理机制,从Windows原理来理解面向对象编程的原理,并对Windows内部的API函数作了相应的分析,在此基础上,通过调用多个API函数实现窗口程序的编写。 相似文献
928.
Single or/and multipeak solitons in plasma under relativistic electromagnetic field are reviewed. The incident electromagnetic
field is allowed to have a zero or/and nonzero initial constant amplitude. Some interesting numerical results are obtained
that include a high-number multipeak laser pulse and single or/and low-number multipeak plasma wake structures. It is also
shown that there exists a combination of soliton and oscillation waves for plasma wake field. Also, the electron density exhibits
multi-caviton structure or the combination of caviton and oscillation. A complete eigenvalue spectrum of parameters is given
wherein some higher peak numbers of multipeak electromagnetic solitons in the plasma are included. Moreover, some interesting
scaling laws are presented for field energy via numerical approaches. Some implications of results are discussed.
相似文献
929.
L. Qian Z. Xu F. Teng X.-X. Duan Z.-S. Jin Z.-L. Du F.-S. Li M.-J. Zheng Y.-S. Wang 《Journal of nanoparticle research》2007,9(3):523-527
Efficiency of polymer light-emitting diodes (PLEDs) with poly(2-methoxy-5-(2-ethyl hexyloxy)-p-phenylene vinylene) (MEH-PPV) as an emitting layer was improved if a dehydrated nanotubed titanic acid (DNTA) doped hole-buffer
layer polyethylene dioxythiophene (PEDOT) was used. Photoluminescence (PL) and Raman spectra indicated a stronger interaction
between DNTA and sulfur atom in thiophene of PEDOT, which suppresses the chemical interaction between vinylene of MEH-PPV
and thiophene of PEDOT. The interaction decreases the defect states in an interface region to result in enhancement in device
efficiency, even though the hole transporting ability of PEDOT was decreased. 相似文献
930.
Jingchang Sun Hongwei Liang Jianze Zhao Ziwen Zhao Guotong Du 《Applied Surface Science》2007,253(11):5161-5165
ZnO films were deposited on c-plane Al2O3 substrates by pulsed laser deposition. The etching treatments for as-grown ZnO films were performed in NH4Cl aqueous solution as a function of NH4Cl concentration and etching time. It was found that NH4Cl solution is an appropriate candidate for ZnO wet etching because of its controllable and moderate etching rate. The influence of etching treatment on the morphology, optical and electrical properties of the ZnO films has been investigated systematically by means of X-ray diffraction, atomic force microscope, photoluminescence and Hall effect. The results indicated that the surface morphology and optical properties of the films were highly influenced by etching treatment. 相似文献