The study of the telepresence robot as a tool for telecommunication from a remote location is attracting a considerable amount of attention. However, the problem arises that a telepresence robot system does not allow the volume of the user's utterance to be adjusted precisely, because it does not consider varying conditions in the sound environment, such as noise. In addition, when talking with several people in remote location, the user would like to be able to change the speaker volume freely according to the situation. In a previous study, a telepresence robot was proposed that has a function that automatically regulates the volume of the user's utterance. However, the manner in which the user exploits this function in a practical situation needs to be investigated. We propose a telepresence conversation robot system called “TeleCoBot.” TeleCoBot includes an operator's user interface, through which the volume of the user's utterance can be automatically regulated according to the distance between the robot and the conversation partner and the noise level in the robot's environment. We conducted a case study, in which the participants played a game using TeleCoBot's interface. The results of the study reveal the manner in which the participants used TeleCoBot and the additional factors that the system requires.

We consider the problem of preserving data in intermittently connected sensor networks wherein sensor nodes do not always have connected paths to the base stations. The generated data is first stored inside the network before being uploaded to the base station when uploading opportunities arise. Each node has both limited energy level and limited storage space, and is associated with a probability of failure. To guarantee that at any moment, each generated data item is available for being uploaded in the presence of node failure, we propose to replicate K copies of each data item in the network, where K depends upon the node failure probability. We refer to the problem as Data K-Availability Problem (DKAP). DKAP is naturally divided into two phases: K-Availability creation and K-Availability maintenance. For K-Availability creation, we show that the problem is NP-hard for arbitrary data sizes, and that it is equivalent to minimum cost flow problem for unit data sizes. For K-Availability maintenance, we show that it is NP-hard even for unit data sizes and design a centralized greedy heuristic. We further design an efficient and low-overhead distributed algorithm, which is applicable to both phases, and show using extensive simulations that it performs close to the heuristic.

Internet-based data intensive sensor networks (DISNs) are sensor networks wherein large volume of different types of sensory data are sensed and generated from the physical world, and queried by multiple users simultaneously. One critical issue in Internet-based DISNs is how to support multiple user queries simultaneously in an efficient manner, in terms of query response time, query loss ratio and sensor node energy consumption. In this paper, we formulate and study multi-user data query problem in DISNs and present our solution. Specifically, we present our design, implementation, and evaluation of LiteWS, a web service system aiming to enhance multi-user queries in Internet-based DISNs. We propose a simple caching technique and give an analytical model of how to reduce query loss ratio in our system. Through extensive experiments based on Crossbow IRIS motes, we evaluate the system performance of LiteWS under both correlated and uncorrelated query traffic. We show the performance with data caching is much better than the one without; particularly, the average query response time of LiteWS is improved 5 to 10 times and the query loss rate is improved 2 times.

Nutrients run-off from land causes environmental problem due to the eutrophication of rivers, lakes or reservoirs. These run-off are considered to affect not only water quality but sea bottom soil status in enclosed bay which has little exchange of sea water to and from outer sea. This study describes estimation of the load of total nitrogen and total phosphorus in Ago bay and its watershed which is typical enclosed bay in Japan, using geographical information system. Fist, we describe the model of discharged load on mesh base. Then generation of land use map and digital elevation model are introduced. Finally, the load of COD, TN, TP of watershed are estimated by the mesh model and per unit production method. The result of the two methods is compared.