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Auflistung nach Autor:in "Fukuda, Akira"

1 - 3 von 3
  • Konferenzbeitrag
    Hot topic detection in local areas using twitter and wikipedia
    (ARCS 2012 Workshops, 2012) Ishikawa, Shota; Arakawa, Yutaka; Tagashira, Shigeaki; Fukuda, Akira
    As microblog services become increasingly popular, spatial-temporal text data has increased explosively. Many studies have proposed methods to spatially and temporally analyze an event, indicated by the text data. These studies have aimed a extracting the period and the location in which a specified topic frequently occurs. In this paper, we focus on a system that detects hot topic in a local area and during a particular period. There can be a variation in the words used even though the posts are essentially about the same hot topic. We propose a classification method that mitigates the variation of posted words related to the same topic.
  • Konferenzbeitrag
    A mobile sink-initiated proactive routing protocol for deadline-aware data aggregation method in energy-efficient wireless sensor networks
    (ARCS 2012 Workshops, 2012) Abe, Tatsuya; Arakawa, Yutaka; Tagashira, Shigeaki; Fukuda, Akira
    In this paper, we focus on monitoring environments with wireless sensor networks in which mobile sink nodes traverse sensing fields in a specific spatialtemporal manner and aggregate various types of environmental data with different deadline constraints distributed over sensor nodes. For such environments, we propose an energy-efficient data aggregation method that reduces intermediate transmission in multi-hop communication while guaranteeing predetermined deadlines. The basic approach of the proposed method is to temporarily gather (or buffer) the observed data into several sensor nodes around the moving path of the mobile sink that would meet their deadlines at the next visit. Then, the buffered data is transferred to the mobile sink node when it visits the buffering nodes. We also propose a mobile sink-initiated proactive routing protocol with low cost (MIPR-LC) that efficiently constructs routes to the buffering nodes on each sensor node. Moreover, we simulate the proposed aggregation method and routing protocol to show their effectiveness. Our results confirm that the MIPR-LC method can reduce energy consumption by up to 23\% when compared with a simple routing protocol. In addition, the mobile sink nodes can gather almost all of the observed data within the deadline.
  • Konferenzbeitrag
    A robust generation technique of common information based on characteristic of multipath fading channel by shaking handheld devices
    (ARCS 2012 Workshops, 2012) Iwamoto, Tomohiro; Tagashira, Shigeaki; Arakawa, Yutaka; Fukuda, Akira
    A rapid increase in handheld devices with wireless communication capabilities, such as cellular phones and smart phones, enables data communication in face-toface situations. The easy realization of secure data communication in such situations is necessary for ensuring safe and reliable networking environments as short-range wireless networks become more popular. One approach involving the generation of secret keys in each communication device using variations of the received signal strength indication (RSSI) values has been proposed in literature. However, it has a problem in that there are positions where eavesdroppers are able to obtain RSSI values that are highly correlated with those of legitimate devices. To address this problem, we propose a filtering technique that eliminates eavesdroppable parts from RSSI variations. Additionally, it is important to shake either one or both of two legitimate devices to change the propagation, considering that the elimination exploits the periodicity of the shake. Furthermore, we implemented a prototype system realizing the proposed method and evaluated its effectiveness. The results indicate that the proposed method can increase the robustness of common information, which is generated into the secret key without degrading its generation speed.