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31.
通过挤出成型法制备聚丙烯/木粉复合材料(PP/WF),添加一种镧系稀土金属络合物(WBG)成核剂诱导PP/WF复合材料中等规聚丙烯(iPP)形成β晶型。以差示扫描量热和X射线衍射为表征方法,分析成核剂对PP/WF结晶行为的作用,进而研究其对力学性能的影响。结果表明,WBG成核剂能有效地诱导PP/WF产生β-iPP结晶,当WBG的添加量为m(WBG)/m(PP)=0.3/100时其产生的β晶相对含量达到78.75%,β-iPP的相对含量还与PP/WF的冷却速率密切相关;添加WBG提高了复合材料中iPP的结晶温度;WBG成核剂能显著改善复合材料的冲击韧性,但对弯曲和拉伸性能略有不利影响。 相似文献
32.
静电纺丝是一种新型的非纺织成丝技术,具有适用材料体系广泛、纤维尺寸结构可控、工艺简便等特点,是制备连续纳米纤维的重要方法.静电纺丝技术制备的纳米纤维薄膜因具有巨大的纳米表面和网状孔隙结构可调等优势,在超级电容器领域显示出诱人的应用前景.综述了近年来静电纺丝技术在超级电容器电极材料和隔膜材料方面的研究进展,介绍了碳基、金属氧化物和聚合物电极材料高活性纳米纤维的制备方法及电化学行为,以及静电纺丝无纺布作为隔膜材料显示出的巨大优势,并总结了制约静电纺丝走向商业化的不利因素,如产率低、薄膜强度不足、喷丝不稳定等,最后介绍了近年来静电纺丝技术在结构可控、规模化制备的产业进展,并展望了其在超级电容器领域中的商业化应用前景. 相似文献
33.
34.
并行设计过程建模及优化 总被引:8,自引:1,他引:8
设计过程建模及优化对于缩短产品开发时间、提高企业的竞争力具有重大意义,本文提出了面向对象(O-O:Object-Oriented)的设计和并行设计过程建模方法,随后以二级圆柱直齿减速器的设计为例,介绍了以O-O过程模型为基础,以设计结构矩阵为工具的设计活动重组,并比较了重组前后所用时间,取得了明显的效果。 相似文献
35.
数据库图形化技术是综合数据库技术和图形技术而形成的一种新兴技术,在当前的互联网中有很大的应用前景。本文介绍了数据库图形化技术,包括ActiveX控件和开放式数据库互连(ODBC)在接入网(AN)管理系统中的应用。 相似文献
36.
37.
本文提出了求解控制变量受区间约束情形的离散时间线性系统最优控制的遗传算法,在遗传算法框架下给出了离散时间线性系统最优控制问题可行解的编码及初始化方法,设计了选择、交叉、变异等遗传算子,并对初始化方法及各种遗传算子的可行性给出理论分析。 相似文献
38.
本文针对空间实体结构的稳定性问题,给出三维系统的广义稳定性概念.考虑材料非线性以及系统接近失稳时可能出现的几何非线性,采用非线性稳定性理论研究空间实体结构的稳定性和承载能力,给出失稳的判别准则,并将此理论和方法应用于重力坝-地基系统的稳定性分析中,使分析具有更为严谨的力学理论基础.计算分析表明,此方法理论正确,结果可靠,具有广阔的工程应用前景. 相似文献
39.
Prony算法在电力系统负荷动态模型辨识中的应用研究 总被引:7,自引:3,他引:7
提出了电力系统负荷动态模型辨识的Prony算法,给出了该算法所需要的Prony模型,并对传 统Prony算法进行了发展。实际算例的数值试验结果显示了该算法对于负荷动态模型辨识的 有效性和准确性。 相似文献
40.
Future wired-wireless multimedia networks require diverse quality-of-service (QoS) support. To this end, it is essential to
rely on QoS metrics pertinent to wireless links. In this paper, we develop a cross-layer model for adaptive wireless links,
which enables derivation of the desired QoS metrics analytically from the typical wireless parameters across the hardware-radio
layer, the physical layer and the data link layer. We illustrate the advantages of our model: generality, simplicity, scalability
and backward compatibility. Finally, we outline its applications to power control, TCP, UDP and bandwidth scheduling in wireless
networks.
The work by Q. Liu and G. B. Giannakis are prepared through collaborative participation in the Communications and Networks
Consortium sponsored by the U.S. Army Research Laboratory under the Collaborative Technology Alliance Program, Cooperative
Agreement DAAD19-01-2-0011. The U.S. Government is authorized to reproduce and distribute reprints for Government purposes
notwithstanding any copyright notation thereon. The work by S. Zhou is supported by UConn Research Foundation internal grant
445157.
Qingwen Liu (S’04) received the B.S. degree in electrical engineering and information science in 2001, from the University of Science
and Technology of China (USTC). He received the M.S. degree in electrical engineering in 2003, from the University of Minnesota
(UMN). He currently pursues his Ph.D. degree in the Department of Electrical and Computer Engineering at the University of
Minnesota (UMN).
His research interests lie in the areas of communications, signal processing, and networking, with emphasis on cross-layer
analysis and design, quality of service support for multimedia applications over wired-wireless networks, and resource allocation.
Shengli Zhou (M’03) received the B.S. degree in 1995 and the M.Sc. degree in 1998, from the University of Science and Technology of China
(USTC), both in electrical engineering and information science. He received his Ph.D. degree in electrical engineering from
the University of Minnesota, 2002, and joined the Department of Electrical and Computer Engineering at the University of Connecticut,
2003.
His research interests lie in the areas of communications and signal processing, including channel estimation and equalization,
multi-user and multi-carrier communications, space time coding, adaptive modulation, and cross-layer designs. He serves as
an associate editor for IEEE Transactions on Wireless Communications since Feb. 2005.
G. B. Giannakis (Fellow’97) received his Diploma in Electrical Engineering from the National Technical University of Athens, Greece, 1981.
From September 1982 to July 1986 he was with the University of Southern California (USC), where he received his MSc. in Electrical
Engineering, 1983, MSc. in Mathematics, 1986, and Ph.D. in Electrical Engineering, 1986. After lecturing for one year at USC,
he joined the University of Virginia in 1987, where he became a professor of Electrical Engineering in 1997. Since 1999 he
has been a professor with the Department of Electrical and Computer Engineering at the University of Minnesota, where he now
holds an ADC Chair in Wireless Telecommunications.
His general interests span the areas of communications and signal processing, estimation and detection theory, time-series
analysis, and system identification -- subjects on which he has published more than 200 journal papers, 350 conference papers
and two edited books. Current research focuses on transmitter and receiver diversity techniques for single- and multi-user
fading communication channels, complex-field and space-time coding, multicarrier, ultra-wide band wireless communication systems,
cross-layer designs and sensor networks.
G. B. Giannakis is the (co-) recipient of six paper awards from the IEEE Signal Processing (SP) and Communications Societies
(1992, 1998, 2000, 2001, 2003, 2004). He also received the SP Society’s Technical Achievement Award in 2000. He served as
Editor in Chief for the IEEE SP Letters, as Associate Editor for the IEEE Trans. on Signal Proc. and the IEEE SP Letters, as secretary of the SP Conference Board, as member of the SP Publications Board, as member and vice-chair of the Statistical
Signal and Array Processing Technical Committee, as chair of the SP for Communications Technical Committee and as a member
of the IEEE Fellows Election Committee. He has also served as a member of the IEEE-SP Society’s Board of Governors, the Editorial
Board for the Proceedings of the IEEE and the steering committee of the IEEE Trans. on Wireless Communications. 相似文献