Applications, such as grid computing, remote backup, and contents distribution, transfer bulk data over wide-area networks. These applications schedule work to satisfy the user requirements. Guaranteeing the performance of data transfer is helpful for scheduling these applications. Diffserv AF is a QoS control method that guarantees data transfer performance. However, the throughput of conventional TCPs is much lower than the reserved bandwidth in congested Diffserv AF networks. Some high-speed protocols reduce the difference between the reserved bandwidth and the average throughput. However, other traffic in the networks influences the throughput of these high-speed protocols. The insufficient throughput stability exists when the background traffic throughput frequently changes in congested networks. Our purpose is to improve the network bandwidth utilization and to make it possible to reserve more bandwidth in Diffserv AF networks. We propose a data transfer method that uses two kinds of TCP flows. One TCP flow reserves network bandwidth and controls the window size to reduce the difference between the throughput and the reservation bandwidth. The other TCP flow transfers data without bandwidth reservation and flow control. This method allows for a higher throughput when the network is uncongested and reduces the difference between the reserved bandwidth and the throughput in congested networks.
Today, billions of users use the Internet to access multimedia information on the World Wide Web (WWW). Most users, however, are given low-speed connection to the Internet and are often irritated by the long transmission time of WWW pages. Therefore, it is very important for information providers to tailor the presentation of information to a user's network environment. In this paper, we propose an architecture for a WWW server with a media scaling mechanism. The WWW server can control the transmission time of WWW pages based on the transmission time threshold specified by the information providers. We also describe our implementation of the WWW server and discuss some experimental results.
IoT (Internet of Things) security is a critical issue while IoT is a big trend where a huge number of devices would be connected to the Internet. To protect physical devices from intruders, we proposed the IoT Agent Platform mechanism to separate IoT functions from physical devices and to run isolated IoT functions on cloud environment. The Dripcast framework which provides transparent method call on cloud objects enables us to handle virtual clones for physical devices easily and intuitively. In this paper, we propose to extend the IoT Agent Platform to support m-cloud mechanism which reduces the risk of revealing privacy information contained in sensor values. This enables to secure data held by virtual clones, that is agent objects on cloud environment.
Recently, the amount of scientific data has been increasing because of technological advancement in measurement and high-performance computing. As the result, visualization technologies are becoming increasingly important to analyze the scientific data. Among visualization technologies, SAGE is gathering attention of scientists in these days. It not only enables the visualization of tens of million pixel-class high-resolution image but also has the potential to realize the collaboration environment where scientists can work together for their common research purpose. However, there remain still technical issues in SAGE, since it is still in the process of development. A problem of application operability, which prevents SAGE users from efficiently operating various applications on SAGE, is targeted in this paper. This problem is caused from the architectural design that SAGE users have to manage window-related operation and application-related operation from different interfaces. For solving the problem, we have developed a built-in application control module for SAGE. Our built-in application control module unifies the separate interfaces for window management and application operation. As a result, users can control application from a unified user interface, SAGE UI.
Urban conditions are monitored by a wide variety of sensors that measure several attributes, such as temperature and traffic volume. The correlations of sensors help to analyze and understand the urban conditions accurately. The correlated attribute pattern (CAP) mining discovers correlations among multiple attributes from the sets of sensors spatially close to each other and temporally correlated in their measurements. In this paper, we develop a visualization system for CAP mining and demonstrate analysis of smart city data. Our visualization system supports an intuitive understanding of mining results via sensor locations on maps and temporal changes of their measurements. In our demonstration scenarios, we provide four smart city datasets collected from China and Santander, Spain. We demonstrate that our system helps interactive analysis of smart city data.
WiFi Positioning System (WPS) plays important role in Ubiquitous applications. It shows shorter response time than GPS and provides more precise position than Cell towers. It is widely used in hybrid positioning systems, e.g. GPS and WPS. The main problem of WPS is how to collect WiFi Access Point (AP) positions because the most of AP positions are not published. So thus, WPS providers collect AP positions by themselves or rely on the WPS user's report. There are several WPS provided, some are commercial system and the others are voluntarily provided. Outdoor position estimation method are already established in commercial system, however, the indoor case requires some more researches. It is necessary to keep voluntarily WPSs. In this paper, we propose an open method to select precise position reported by users to keep WPS estimation accuracy. The proposed method is basically based on the precision preservation methods used in GPS. WPS does not have the same degree of accuracy as GPS, it should be verified the effectiveness in WPS. We have some consideration about the applicability of the proposed method.
This paper introduces a sensor network testbed, X-sensor, that integrates multiple sensor networks deployed at different sites. X-sensor provides three functionalities: (a) a sensor network search which enables users to find a sensor networks appropriate for experiment and data acquisition, (b) a sensor data archive which provides users with various sensor data acquired by sensor nodes, and (c) an experimental testbed which enables remote users to evaluate their proposed methodologies.
