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In diagnostic ultrasound imaging, microbubble-based contrast agents are currently used to enhance blood flow signals. The microbubbles in the blood vessels have various diameters and various resonant frequencies. Therefore, only some bubbles will be stimulated by a transmission pulse with a single frequency component. In this report, we propose a multiple-pulse transmission method with different frequencies...
The concept of peer-assisted content delivery networks (CDNs) lets other nearby altruistic clients forward requested content files instead of the source servers, which works to localize overall traffic. Our prior work proposed a traffic engineering scheme to localize traffic in peer-assisted CDNs. To induce altruistic clients to download content files that are most likely to contribute to localizing...
Peer-assisted content distribution technologies have been attracting attention. By using not only server resources but also the resources of end hosts (i.e., peers), we can reduce the offered load on servers as well as utilization of the access bandwidth of the servers. However, offered traffi to the network may increase because the traffi exchanged between peers passes across the network. Specificall,...
Designing network topologies requires simultaneous consideration of multiple criteria, such as network cost and reliability. So, the author applied the analytic hierarchy process, a way to make a rational decision considering multiple criteria, to network topology evaluation. However, the time required to construct the candidate topology set greatly increases as the network scale grows. This paper...
Video streaming with HDTV or UHDV quality will be provided and widely demanded in the future. However, the transmission bit-rate of high-quality video streaming is quite large, so generated traffic flows will cause link congestion. Therefore, when providing streaming services of rich content, it is important to flatten the link utilization, i.e., reduce the maximum link utilization. To achieve this...
It is known that there exist Triangle Inequality Violations (TIVs) with respect to network Quality of Service (QoS) metrics such as latency between nodes in the Internet. This motivates the exploitation of QoS-aware routing overlays. To find an optimal overlay route, we would usually need to examine all the possible overlay routes. However, this requires both measuring QoS between all node pairs and...
When designing network topology, we need to simultaneously consider multiple criteria, such as network cost and reliability. Therefore, the author applied the analytic hierarchy process (AHP) to network topology evaluation. However, the time required to construct a candidate topology set drastically increases as the network scale grows. So, the author proposed an efficient method for constructing...
When a link or node failure occurs in a network, flows are detoured and therefore the hop counts of the flows increase. This increase could drastically deteriorate the quality of a network. The flow hop length stability as well as network connectivity is important for network reliability. We investigate a network design method that improves stability and connectivity of a network during a failure...
As a promising solution to manage the huge workload of large-scale VoD services, managed peer-assisted CDN systems, such as P4P has attracted attention. Although the approach works well in theory or in a controlled environment, to our best knowledge, there have been no general studies that address how actual peers can be incentivized in the wild Internet; thus, deployablity of the system with respect...
We describe a method of adaptively controlling bandwidth allocation to flows for reducing the file transfer time of short flows without decreasing throughput of long-duration large flows. According to the rapid increase in Internet traffic volume, effective traffic engineering is increasingly required. Specifically, the traffic of long-duration large flows due to the use of peer-to-peer applications,...
Network topology seriously affects network cost, path length, distribution of link load, and reliability, for example, so we need to consider these multiple criteria with different units simultaneously when designing network topology. The analytic hierarchy process (AHP) is a way to make a rational decision considering multiple criteria. Using AHP, we can reflect the relative importance of each criterion...
The transmission bandwidth consumed by delivering rich content, such as movie files, is enormous, so it is urgent for ISPs to design an efficient delivery system minimizing the amount of network resources consumed. To efficiently deliver web content, a content delivery networks (CDNs) have been widely used. CDN providers collocate a huge number of servers within multiple ISPs without being informed...
When a link or node fails, flows are detoured around the failed portion, so the hop count of flows and the link load could change dramatically as a result of the failure. As real-time traffic such as video or voice increases on the Internet, ISPs are required to provide stable quality as well as connectivity at failures. For ISPs, how to effectively improve the stability of these qualities at failures...
We propose a method of identifying anomalous traffic sources using flow statistics. We have investigated a way of detecting whether or not anomalies occur by observing the behavior of several time-series of flow statistics such as the number of flows. After detecting the occurrences of network anomalies, we need to identify the source of the anomalies. In this paper, we describe a method of identifying...
We present a method of detecting network anomalies, such as DDoS (distributed denial of service) attacks and flash crowds, automatically in real time. We evaluated this method using measured traffic data and found that it successfully differentiated suspicious traffic. In this paper, we focus on cyclic traffic, which has a daily and/or weekly cycle, and show that the differentiation accuracy is improved...
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