排序方式: 共有103条查询结果,搜索用时 15 毫秒
81.
PAUL KELLETT 《Fiber and Integrated Optics》2013,32(5):289-303
This article details the evolution of Ethernet into Gigabit Ethernet and how this LAN-based technology has undergone major transformations over time. From its data rates and distances to supported media and functionality, Ethernet has greatly improved, enabling it to surmount many of its former limitations and in so doing to expand beyond the LAN into the MAN and now even the WAN. In this article, Pioneer Consulting explores the evolution further by focusing on some of the major technological directions in the Ethernet equipment industry. 相似文献
82.
S. De Maesschalck 《Fiber and Integrated Optics》2003,22(2):63-77
In this article the influence of the asymmetric nature of (IP) traffic on the cost of the underlying optical transport network is investigated over a time frame of six years using a realistic traffic forecast for a European fiber-optic network. The currently deployed transport networks contain bidirectional optical line systems and are thus inherently symmetric, although the traffic that has to be conveyed over those networks is asymmetric. This article shows that a cost reduction of up to 38% can be obtained if the bidirectional line systems are replaced by unidirectional ones. 相似文献
83.
A theoretical description of charge reorganization energies in molecular organic P‐type semiconductors 下载免费PDF全文
Charge transport properties of materials composed of small organic molecules are important for numerous optoelectronic applications. A material's ability to transport charges is considerably influenced by the charge reorganization energies of the composing molecules. Hence, predictions about charge‐transport properties of organic materials deserve reliable statements about these charge reorganization energies. However, using density functional theory which is mostly used for the predictions, the computed reorganization energies depend strongly on the chosen functional. To gain insight, a benchmark of various density functionals for the accurate calculation of charge reorganization energies is presented. A correlation between the charge reorganization energies and the ionization potentials is found which suggests applying IP‐tuning to obtain reliable values for charge reorganization energies. According to benchmark investigations with IP‐EOM‐CCSD single‐point calculations, the tuned functionals provide indeed more reliable charge reorganization energies. Among the standard functionals, ωB97X‐D and SOGGA11X yield accurate charge reorganization energies in comparison with IP‐EOM‐CCSD values. © 2016 Wiley Periodicals, Inc. 相似文献
84.
《Journal of computational chemistry》2017,38(9):594-600
DFT method can severely overestimate the response properties for π‐conjugation systems. The range‐separated exchange and recently developed optimal IP‐tuning process are evaluated on the prediction of static second hyperpolarizabilities of streptocyanines of increasing molecular length. The finite field results have shown that the exact exchange at midium and long distance can relieve only a part of the overshooting but still beyond satisfaction. The exact exchange at short distance has the oppsite effects showing the failure of converntional hGGA. The optimal tuned range‐separated exchange functionals show little improvements performing worse than the default ones. Importantly, the electronic structure–property relationship, bond order alternation‐γ , is not well established with DFT method. © 2017 Wiley Periodicals, Inc. 相似文献
85.
Some polarity terms of two groups of nitrogen-containing surfactants ( six alkanolamides and nine polyoxyethylenated long chain amines) are measured through gas chromatography. The apparent methanol carbon number (CMeOH) and polarity index (IP) values are determined on the investigated surfactants as stationary phases in packed columns. Similarly, CMeOH and IP values are determined on simulated hydrophobic tail (SHT)models. The obtained results reveal that the introduction of SHT approach permits the distinction between the polarities of different surfactants and their head groups. The measured polarity terms are discussed as related to hydrophile-lipophile balance (HLB) number and the hydrophobic group carbon number (RCN). Some equations relating the measured polarity values and these variable have been developed. 相似文献
86.
Jacobus Kuijt 《Analytica chimica acta》2003,488(2):135-171
A wide-ranging overview of room temperature phosphorescence in the liquid state (RTPL1) is presented, with a focus on recent developments. RTPL techniques like micelle-stabilized (MS)-RTP, cyclodextrin-induced (CD)-RTP, and heavy atom-induced (HAI)-RTP are discussed. These techniques are mainly applied in the stand-alone format, but coupling with some separation techniques appears to be feasible. Applications of direct, sensitized and quenched phosphorescence are also discussed. As regards sensitized and quenched RTP, emphasis is on the coupling with liquid chromatography (LC) and capillary electrophoresis (CE), but stand-alone applications are also reported. Further, the application of RTPL in immunoassays and in RTP optosensing—the optical sensing of analytes based on RTP—is reviewed. Next to the application of RTPL in quantitative analysis, its use for the structural probing of protein conformations and for time-resolved microscopy of labelled biomolecules is discussed. Finally, an overview is presented of the various analytical techniques which are based on the closely related phenomenon of long-lived lanthanide luminescence. The paper closes with a short evaluation of the state-of-the-art in RTP and a discussion on future perspectives. 相似文献
87.
N—苯基马来酰亚胺与苯乙烯共聚合的研究 总被引:4,自引:0,他引:4
对N-苯基马来酰亚胺与苯乙烯悬浮聚合体系作了系统的研究,找到适合该体系的最佳反应温度,单体用量化,引发剂用量,搅拌速度以及水油比。通过采用聚乙烯醇,CMC-Na盐,无机粉末混合分散剂,得到稳定的悬浮体系,产物为颗粒起先均匀分布在0.5-0.7mm范围内的IP树脂。 相似文献
88.
This paper addresses the parallel machine scheduling problem in which the jobs have distinct due dates with earliness and tardiness costs. New lower bounds are proposed for the problem, they can be classed into two families. First, two assignment-based lower bounds for the one-machine problem are generalized for the parallel machine case. Second, a time-indexed formulation of the problem is investigated in order to derive efficient lower bounds throught column generation or Lagrangean relaxation. A simple local search algorithm is also presented in order to derive an upper bound. Computational experiments compare these bounds for both the one machine and parallel machine problems and show that the gap between upper and lower bounds is about 1.5%. 相似文献
89.
针对在传统移动IP中用户只能被动使用已知的网络服务问题,提出了支持主动式网络服务发现的移动IP方案.本方案在传统移动IP基础上,引入基于客户/服务模型的主动服务发现机制,并制定具体的通信过程及各种消息的格式,实现了对瘦客户的支持.同时针对带宽紧张问题,设计了优化过滤机,实行结果过滤,避免了不必要的结果的发送,提高了带宽利用率.模拟实验表明了该系统较好地支持了移动IP中主动服务发现,具有较好的实用性和应用价值。 相似文献
90.
WenXi Liang YuTong Li MiaoHua Xu XiaoHui Yuan ZhiYuan Zheng Yi Zhang Feng Liu ZhaoHua Wang HanMing Li Zhan Jin ZhiYi Wei Wei Zhao YingJun Li Jie Zhang 《中国科学G辑(英文版)》2008,51(10):1455-1462
Image Plate (IP) is convenient to be used and very suitable for radiation detection because of its advantages such as wide
dynamic range, high detective quantum efficiency, ultrahigh sensitivity and superior linearity. The function mechanism and
characteristics of IP are introduced in this paper. IP was employed in the study of hot electrons generated from intense laser-plasma
interaction. The angular distribution and energy spectrum of hot electrons were measured with IP in the experiments. The results
demonstrate that IP is an effective radiation detector for the study of laser-plasma interaction.
Supported by the National Natural Science Foundation of China (Grant Nos. 10675164, 60621063, 10334110, 10575129, 10510490,
and 10390161), the Funds of the Chinese Academy of Sciences for Key Topics in Innovation Engineering (Grant No. KJCX2-YW-T01)
and the National High-Tech ICF Program 相似文献