著者

Mukai Kohki Watanabe Keita Kimura Yuuta

出版者

Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physics

雑誌

Jpn J Appl Phys (ISSN:00214922)

巻号頁・発行日

vol.49, no.4, pp.04DH07-04DH07-4, 2010-04-25

被引用文献数

3

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The lattice constant distribution inside a columnar InAs/GaAs quantum dot (QD) and its crystal orientation dependence were evaluated by grazing incidence X-ray diffraction (GIXD) measurement. The QDs were grown by stacking Stranski-krastanow (SK)-type InAs QDs directly in the growth direction with very thin GaAs interval layers. We evaluated the dependence of the in-plane lattice constant on QD height by GIXD measurement using equipment available for laboratories. We found that the lattice constants at the top and bottom of the QDs were almost the same when the height and diameter of the QDs were almost equal. As the number of stacks was increased to grow high QDs, the lattice constant at the QD top became larger in the [1-10] direction than in the [110] direction, but this relationship was reversed at the bottom. We consider that GIXD measurement with compact equipment will contribute to the swift and efficient development of QD devices.

著者

TAKAHASHII Tsubasa KITAGAWA Hiroyuki WATANABE Keita

出版者

電子情報通信学会

雑誌

IEICE transactions on information and systems (ISSN:09168532)

巻号頁・発行日

vol.E93.D, no.6, pp.1403-1413, 2010-06

被引用文献数

1 2

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Social bookmarking services have recently made it possible for us to register and share our own bookmarks on the web and are attracting attention. The services let us get structured data: (URL, Username, Timestamp, Tag Set). And these data represent user interest in web pages. The number of bookmarks is a barometer of web page value. Some web pages have many bookmarks, but most of those bookmarks may have been posted far in the past. Therefore, even if a web page has many bookmarks, their value is not guaranteed. If most of the bookmarks are very old, the page may be obsolete. In this paper, by focusing on the timestamp sequence of social bookmarkings on web pages, we model their activation levels representing current values. Further, we improve our previously proposed ranking method for web search by introducing the activation level concept. Finally, through experiments, we show effectiveness of the proposed ranking method.