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The Remote Experimentation Centre (REC) in Japan has been preparing to replicate the full dataset of ITER over 10 000 km distance. In such a multi-site data repository environment, the data location informing service will be essential to find and retrieve the data efficiently. Considering the long latency time and the self sustainability of remote sites, the data location database should be running at each repository site. Multi-master asynchronous replication between cooperating databases will be essential to realize the remote experimental collaborations in fusion research. This study has investigated the functional differences of some relational databases and found that Postgres BDR has the expected database replication capabilities. Bi-directional replication (BDR) tests by using the LHD database and SNET revealed that the throughputs are sufficient for remote collaborations in fusion experiments.

The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident has resulted in the contamination of the environment in Gunma Prefecture with radioisotope cesium (radio-Cs, 134Cs and 137Cs). Concentrations of radio-Cs >500Bqkg-1 were found in wakasagi (Hypomesus nipponensis) in Lake Onuma at the top of Mount (Mt.) Akagi in August 2011. To explain the mechanism of this contamination, monitoring studies have been conducted around Lake Onuma by measuring radio-Cs concentrations in samples of fish, aquatic plants, plankton, lake water, lake sediments, and surrounding soil. The leachability of radio-Cs was evaluated using sequential extraction by Tessier et al. The total concentration of radio-Cs in Lake Onuma ecosystems decreased gradually with time. In the brown forest soil, radio-Cs concentrations of 2000 to 6000Bqkg-1 were detected. The abundance ratio of the easy-elution form (exchangeable and carbonate forms) in the samples was

Developing effective and fast data transfer system for the huge amount data between Europe and Japan is a critical issue for the ITER Remote Experimentation Center (REC). To implement the system, effective data transfer methods and wide bandwidth international network are required.This paper describes results of data transfer experiments. We have evaluated two data transfer methods: Packet Pacing and MMCFTP. By using Packet Pacing and 2.4 Gbps line, we achieved 2.2 Gbps data transfer from NIFS to IFERC. By using MMCFTP and 10 Gbps line, we achieved 2.5 Gbps data transfer from NIFS to Dublin, Ireland. Furthermore, by using MMCFTP and 100Gbps line, we successfully achieved the stable transmission of 1PB of data at approximately 84 Gbps, one of the world’s fastest transmission speeds.This paper also describes the upgrade plan of SINET (a Japanese academic backbone network), which is used for ITER and REC communications. SINET will be upgraded to the network based on 100-Gigabit Ethernet technology in April 2016. Furthermore, direct lines of 20 Gbps (10 Gbps × 2) between Japan and Europe will be introduced. These direct lines will reduce latency between Europe and Japan and will realize higher speed data transfer., •This paper presents fast data transfer experiments using packet pacing and mmcftp and results.•An upgrade plan of Japanese Academic Network SINET is also described.•To send the huge amount of data from ITER to the ITER Remote Experiment Center (REC), effective transfer method and super high-speed internationalnetwork are required.•This paper presents a progress of the investigation for fast transfer method.

We propose an extension of distcloud-fs for achieving a global distributed POSIX file system in intercloud environment. The file system works in intercloud environment, that is, on the top of multiple independent cloud services. The important capability of the intercloud extension is that there is no need for users to take care of infrastructure layer, while the file system stores data into multiple cloud services, transparently and automatically. As the result, cloud users may have diversity about vendors and locations for data platform, as discussed in various intercloud research projects. In this paper, we describe the architecture of the distcloud-fs and its intercloud extension. We also describe design and implementation of the prototype and discuss some typical use cases of the file system with practical demonstrations.

Technical verification has been progressing for high efficiency data replication between ITER and the Remote Experimentation Centre (REC) in Japan. Transferring a huge amount of data simultaneously to multiple destinations might cause excessive loads and network bandwidth on the sender so that daisy-chained relay transfer would be a considerable solution. This study demonstrates how efficiently the replication relay could be realized for the next-generation fusion experiments, such as ITER and JT-60SA. All the LHD data were consecutively sent to the REC through the global loop path (GLP: Toki - Gifu - Tokyo - Amsterdam - New York - Los Angeles - Tokyo - Aomori - Rokkasho) on SINET5 L2VPN, whose round-trip time is almost 400 ms. MMCFTP was used for the data transferring application. In both the Japan domestic path and the GLP cases, every transfer shows a very stable flattop speed as the preset 8 Gbps. However, longer gap times were needed in MMCFTP initial negotiation to establish numerous sessions. The performance optimized NVMe and iSCSI striped storages have shown higher throughputs than the ITER estimated initial data rate of 2 GB/s. Those knowledge enable the design optimization of not only the sender/receiver servers with their storages but also the intermediate relay server system.

SINET5 is a new 100-Gbps-based academic backbone network, which started full-scale operations in April 2016. It uses multi-protocol label switching-transport profile (MPLS-TP) systems and reconfigurable optical add-drop multiplexers (ROADMs) to create a nationwide network and has more than 50 backbone IP routers to provide a wide range of services, such as several virtual private network (VPN) services. It provides end-to-end data communications up to 100 Gbps throughput, minimized-latency, and software-defined networking (SDN)-friendly functions to researchers in every Japanese prefecture. SINET5 is also a platform for dynamic inter-cloud connections and network functions visualization (NFV) services. This paper brief review of the network architecture, and describes new featured services, SDN-oriented layer-2 on-demand VPN services, and NFV functions. Field test results for SINET5 performance are also reported.

In recent years, as mobile devices increase, the demands for measuring the available bandwidth in a wireless network increase more and more to provide high quality network services. The available bandwidth is one of the most important parameters to determine the sending rate in WAN optimization. Pathload [2] is a technique to measure the available bandwidth by detecting the point where the receiving rate becomes lower than the sending rate of test packets. However, Pathload misdetects this point in mobile networks with packet losses caused by fading, interference, and so on. So, we propose a method to measure the available bandwidth by using correlation coefficients between the sending rate and packet loss rate, and then evaluate the accuracy of the proposed method.

This paper gives a brief report on a new 100-Gbps academic backbone network, called SINET5, which started full-scale operations in April 2016. SINET5 has more than 50 backbone routers and forms a fully meshed topology by using MPLS-TP systems to provide researchers in every Japanese prefecture with 100-Gbps access, minimized-latency, and SDN-friendly environments. SINET5 gives a multi-layer, dynamically configurable, and performance-tunable platform for a wide range of network applications including inter-cloud services. The multi-layer network design, new functions including SDN and cloud-oriented functions, and field test results on performance and reliability are reported.

The relevance of sensor response to CO and H 2 with the microstructure of the sensing body was investigated for thick-film devices using Co 3 O 4 (0.5 mass%)–SnO 2 composites. When the composite was prepared from constituent oxides by milling in a satellite ball mill for various spans of time (1–12 h), the sensor response to 100 ppm CO, defined as the ratio of the electrical resistance in air to that in the sample gas, was found to reach a maximum as large as about 800 at 6 h of ball-milling (BM). The response to H 2 , in contrast, showed no such marked promotion. SEM observation of the granular state and pore size distribution analyses indicated that increasing BM time gave rise especially to an increase in the volume of pores in the pore size range of 20–35 nm. It is suggested that such a change in microstructure is responsible for the marked promotion of the response to CO, while the same change is not so much effective on the response to the gas (H 2 ) with a much larger diffusion coefficient. For comparison, the composite prepared by an impregnation method was also subjected to the BM treatments. In this case, the response to CO could not be promoted so much even after BM for 18 h, because the heavy coagulations of grains formed in the impregnation process were prevented from being pulverized by BM.

Mesoporous structure and gas-sensing properties of SnO 2 powders prepared by utilizing the self-assembly of a cationic surfactant under different conditions have been investigated. As-prepared SnO 2 powders were characterized with ordered and hexagonal mesoporous structure ( d 1 0 0 ≈4.4 nm) having a small crystallite size of 1.6–2.0 nm, and the size of agglomerated secondary particles tended to decrease with decreasing the concentration of a Sn source and a surfactant in a precursor solution. Treatment of as-prepared powders with phosphoric acid (PA) was effective for depressing the growth of SnO 2 crystallite during calcination at elevated temperatures and then maintaining the ordered mesoporous structure, while the volume of ordered mesopores decreased. However, mesoporous SnO 2 (m-SnO 2 ) powder with a specific surface area of 374 m 2 g −1 could be prepared even after calcination at 600 °C for 5 h by optimizing the preparation conditions. The m-SnO 2 powders exhibited excellent H 2 sensitivity in proportion to surface area and high NO sensitivity comparable to NO 2 sensitivity. However, their resistance levels in air were close to the limit for practical measurement. Surface modification of conventional SnO 2 (c-SnO 2 ) powder with m-SnO 2 was found to be effective for improving gas-sensing properties of c-SnO 2 , while maintaining the sensor resistance in air to be close to that of c-SnO 2 . H 2 sensitivity of the c-SnO 2 modified with m-SnO 2 was lower than that of m-SnO 2 , but NO 2 sensitivity improved markedly by the surface modification with m-SnO 2 .

WAN optimization becomes a well-known technique to improve transmission rate in file transfer applications and interactive applications served in international cloud services. WAN optimization technique can improve transmission speed by using high performance protocols instead of TCP between both ends of wide area network, which has a large round trip time and a high packet loss rate. There are some kinds of high performance protocols, and their effectiveness in improving communication are different from each other based on the characteristics of the networks and applications. When WAN optimization technique is only used at both ends of a heterogeneous network containing networks such as wireless networks, international leased lines, etc. (e.g., access from a mobile device to a foreign cloud data center), improvement in communication is limited because only one high performance protocol is being applied. Therefore, we propose “distributed WAN optimization technique” that dynamically changes high performance protocols and sections to adapt those protocols based on network characteristics and applications.

Due to a mismatch between downloading and caching content, the network may not gain significant benefit from the sophisticated in-network caching of information-centric networking (ICN) architectures by using a basic caching mechanism. This paper aims to seek an effective caching decision policy to improve the content dissemination in ICN. We propose PopCache-a caching decision policy with respect to the content popularity-that allows an individual ICN router to cache content more or less in accordance with the popularity characteristic of the content. We propose an analytical model to evaluate the performance of different caching decision policies in terms of the server-hit rate and expected round-trip time. The analysis confirmed by simulation results shows that PopCache yields the lowest expected round-trip time compared with three benchmark caching decision policies, i.e., the always, fixed probability and path-capacity-based probability, and PopCache provides the server-hit rate comparable to the lowest ones.

Commercial cloud services are growing rapidly, and system architecture that can process large volumes of large-scale data for mobile devices and sensing devices is expected to emerge in the future. Mobile devices will serve as both client terminals and virtual machines in such architecture. However, end-to-end TCP sessions are affected by frequent changes in wireless link quality and movement of virtual machines in the cloud data center. In this paper, we propose a method to improve communication performance by dynamically reselecting and retuning congestion control algorithms and parameters according to changes in link quality and attributes of applications.

This paper describes the progress made in improving the bandwidth-on-demand (BoD) capabilities of the Japanese academic backbone network called SINET3. Since the start of layer-1 BoD services in 2008, we have expanded the service provision area nationwide, introduced functions to improve the usability in response to user requests, and flexibly managed the network resources by taking into account a hybrid accommodation of the layer-1 and layer2/3 services. We are also approaching layer-2 BoD services for applications requiring a relatively small amount of bandwidth. The current status for layer-1 BoD services and the near-future plan for layer-2 BoD services including the initial implementation image are described.

This paper describes the implementation and evaluation of layer-1 bandwidth-on-demand (BoD) capabilities in the Japanese academic backbone network, called SINET3. The network has a nationwide GMPLS-based layer-1 platform and provides reservation-based and signaling-based BoD services. The overall architecture for providing BoD services including its capabilities, user interface, path calculation, and interface to drive the layer-1 platform are described. Actual examples of BoD services and evaluations of the path setup/release time in the network are also presented.