Public works research institute

Tsukuba, Japan

Public works research institute

Tsukuba, Japan
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Agency: European Commission | Branch: FP7 | Program: CP | Phase: ENV.2013.6.4-3 | Award Amount: 6.53M | Year: 2014

Coastal floods are one of the most dangerous and harmful natural hazards affecting urban areas adjacent to shorelines. Rapid urbanisation combined with climate change and poor governance means a significant increase in the risk of local surface flooding coinciding with high water levels in rivers and high tide or storm surges from the sea, posing a greater risk of devastation to coastal communities. The threats posed need to be addressed not just in terms of flood prediction and control, but taking into account governance and socio-economic issues. PEARL brings together world leading expertise in both the domain of hydro-engineering and risk reduction and management services to pool knowledge and practical experience in order to develop more sustainable risk management solutions for coastal communities focusing on present and projected extreme hydro-meteorological events. The project will examine 7 case studies from across the EU to develop a holistic risk reduction framework that can identify multi-stressor risk assessment, risk cascading processes and strengthen risk governance by enabling an active role for key actors. The research programme links risk and root cause assessment through enhanced FORIN methodology, event prediction, forecast and warning, development of adaptive structural and non-structural strategies and active stakeholder participation. The project aims to develop novel technologies and methods that can improve the early warning process and its components; it builds a pan-European knowledge base gathering real case studies and demonstrations of best practice across the EU to support capacity development for the delivery of cost-effective risk-reduction plans. Additionally, the project provides an interface to relevant ongoing tsunami work: it plugs into global databases, early warning systems and processes at WMO, and contributes to community building, development of guidelines and communication avenues at the global level through IWA.

Osti R.,Public Works Research Institute | Egashira S.,Public Works Research Institute | Adikari Y.,Public Works Research Institute
Hydrological Processes | Year: 2013

In this study, the characteristic of multiple glacial lake outburst floods (GLOFs) in the Pho Chu River basin in Bhutanese Himalayas is evaluated to help assess the potential impact. Thorthormi Cho (TC) and Lugge Cho (LC) in the east branch and two unnamed lakes labelled A and B in the west branch of Pho Chu are chosen for the study. Numerical models were employed to simulate different involved processes. The results show that the peak sediment discharge in the east branch of the Pho Chu River by the TC dam breach reached about 5000m3/s (during the first GLOF) at 4km whereas by the LC dam breach is about 600m3/s (second GLOF) at 6km. However, the highest peak hydrographs (sediment and water mixture) calculated during the first and second GLOF are about 10000m3/s at the 18-km section and about 23000m3/s at the 10-km section, respectively. In the west branch of Pho Chu, erosion and depositions are the frequent intermittent local processes during the first GLOF event from Lake A. Because the first event stabilized the irregular river bed profile, there is not much sediment discharge developed during the second GLOF from Lake B. At the 17-km section of the west branch, the peak hydrograph reached about 9000m3/s during the first event against the peak of about 800m3/s during the second event. The results suggest that even if multiple dam breaches occur simultaneously, GLOF surges pass through the main river channel at different times with very different flood characteristics. The differences in travel time and flood characteristics mostly depend on the distributions of bed slope and potential erosion depth along the reach. Further, the amount of sediment accumulated in and transported by each surge is reliant on the temporal geomorphologic setting of the river and therefore on the impact of the previous GLOF on riverbed profile and potential erosion depth. The robustness in peak GLOF hydrographs is associated with sediment flow dynamics. As a consequence, serious inundation of Punakha, Lobeysa and major portion of Wangdue Phodrang is anticipated. © 2011 John Wiley & Sons, Ltd.

Nishizaki I.,Public Works Research Institute | Kato Y.,Public Works Research Institute
Construction and Building Materials | Year: 2011

The authors set out to investigate the durability of the bond between carbon fibre (CF) sheet reinforcement and concrete. They conducted an outdoor exposure test in a moderate climate for 14 years and an immersion test for 6 months on CF sheet bonded to concrete, and then evaluated the adhesive bond properties using the pull-off and peel methods. The pull-off strength slightly decreased after 14 years of exposure, but residual values still indicate quite good adhesive properties. The failure modes for both the initial specimens and the specimens after 14 years of exposure consisted of concrete substrate failures in all cases. This result suggests that the slight decrease in pull-off strength does not necessarily indicate a change in the properties of the bond between CF sheet and concrete. On the other hand, results of the peel tests showed different types of failure modes and seemed more discriminant than those of the pull-off method. As regards specimens immersed in water, pull-off results were in few cases consistent with the peel characterizations, showing significant evolutions in the strength and failure mode. But for most specimens, the two methods provided divergent trends. In the end, this study suggested that the peel test could be relevant for evaluating the durability of the bond between CF sheet and concrete, while the representativeness of the pull-off test remains a matter of discussion. © 2010 Elsevier Ltd. All rights reserved.

The recent development of high-quality boring, which uses foam surfactants, has made it possible to examine the detailed geological constitution and structure of landslide bodies. However, geological information related to landslides has not been obtained appropriately even from undisturbed high-quality drilled cores. Moreover, it has been difficult to distinguish between rocks crushed by landslide movement and the fault breccia in accretionary complexes. We examined the detailed geology of high-quality drilled cores of landslide bodies on the Shimanto Belt and the Chichibu Belt. The fault breccia near the landslide bodies was found to exhibit planar fabrics while the crushed breccias in the landslide bodies showed a random fabric. We discovered that classifying the degree of crushing and inspecting the planar fabrics of rocks are effective in the geological determination of landslide bodies. © 2013 Elsevier B.V.

Tsushima I.,Public Works Research Institute
Journal of Environmental Science and Health - Part A Toxic/Hazardous Substances and Environmental Engineering | Year: 2016

The radioactive fallout from the Fukushima Dai-ichi nuclear power plant disaster in 2011 has flowed into and accumulated in many wastewater treatment plants (WWTPs) via sewer systems; this has had a negative impact on WWTPs in eastern Japan. The behavior of radioactive materials was analyzed at four WWTPs in the Tohoku and Kanto regions to elucidate the mechanism by which radioactive materials are concentrated during the sludge treatment process from July 2011 to March 2013. Furthermore, numerical simulations were conducted to study the safe handling of contaminated sewage sludge stocked temporally in WWTPs. Finally, a dissolution test was conducted by using contaminated incinerated ash and melted slag derived from sewage sludge to better understand the disposal of contaminated sewage sludge in landfills. Measurements indicate that a large amount of radioactive material accumulates in aeration tanks and is becoming trapped in the concentrated sludge during the sludge condensation process. The numerical simulation indicates that a worker's exposure around contaminated sludge is less than 1 µSv/h when maintaining an isolation distance of more than 10 m, or when shielding with more than 20-cm-thick concrete. The radioactivity level of the eluate was undetectable in 9 out of 12 samples; in the remaining three samples, the dissolution rates were 0.5–2.7%. © 2016 Taylor & Francis Group, LLC

Michinobu T.,Tokyo Institute of Technology | Li Y.,Tokyo Institute of Technology | Hyakutake T.,Public Works Research Institute
Physical Chemistry Chemical Physics | Year: 2013

The rapid growth of the click chemistry concept enables the production of a wide variety of functional polymers. Among the new generation of click chemistry reactions, the highly efficient addition reactions between electron-rich alkynes and cyano-based acceptors, referred to as alkyne-acceptor click chemistry, have found promising application possibilities as polymeric chemosensors. The donor-acceptor chromophores, formed by this click chemistry reaction, feature intense charge-transfer (CT) bands in the visible region, but they are hardly fluorescent. Importantly, the chromophores possess two different nitrogen atoms, namely the aniline nitrogen and cyano nitrogen. The recognition of some specific metal cations by different nitrogen atoms in the polymers led to different modes of changes in the absorption spectra. For example, the hard acid of Fe3+ ion was recognized by the aniline nitrogen, resulting in a decrease in the CT bands. On the other hand, the soft acid of the Ag + ion was captured by the cyano nitrogen, leading to a bathochromic shift in the CT bands. Some specific anions, such as CN-, F -, and I- ions, were also recognized by a chemodocimetric detection mode, discoloring the original solutions. When the CT bands decreased upon the addition of analytes, the polymers were found to serve as turn-on fluorescent sensors. In this perspective, the detailed detection modes of the new polymeric chemosensors are fully described.© 2013 the Owner Societies.

Wang F.,Public Works Research Institute | Hidaka T.,Public Works Research Institute | Tsumori J.,Public Works Research Institute
Bioresource Technology | Year: 2014

Anaerobic co-digestion of shredded grass with sewage sludge was investigated under various temperature conditions. The conversion of grass to methane was difficult to achieve under mesophilic conditions, while its methane yield was 0.19. NL/g VS-grass under thermophilic conditions. The mixture ratio of grass to sludge affected the methane yield, and the highest synergistic effect was obtained at a C/N ratio of around 10. In a continuous experiment, hyperthermophilic (80. °C) pretreatment promoted a methane yield of 0.34. NL/g VS-mixture, higher than that under mesophilic and thermophilic conditions (0.20 and 0.30. NL/g VS-mixture, respectively). A batch experiment with hyperthermophilic pretreatment showed that 3. days of treatment was sufficient for subsequent methane production, in which the highest dissolution of particulate COD, carbohydrate and protein was 25.6%, 33.6% and 25.0%, respectively. © 2014 Elsevier Ltd.

Jayawardena A.W.,Public Works Research Institute | Xu P.,CAS Academy of Mathematics and Systems Science | Li W.K.,University of Hong Kong
Chaos | Year: 2010

A method of estimating the Kolmogorov-Sinai (KS) entropy, herein referred to as the modified correlation entropy, is presented. The method can be applied to both noise-free and noisy chaotic time series. It has been applied to some clean and noisy data sets and the numerical results show that the modified correlation entropy is closer to the KS entropy of the nonlinear system calculated by the Lyapunov spectrum than the general correlation entropy. Moreover, the modified correlation entropy is more robust to noise than the correlation entropy. © 2010 American Institute of Physics.

Hidaka T.,Public Works Research Institute | Arai S.,Public Works Research Institute | Okamoto S.,Public Works Research Institute | Uchida T.,Public Works Research Institute
Bioresource Technology | Year: 2013

Adding greenery from public spaces to the co-digestion process with sewage sludge was evaluated by shredding experiments and laboratory-scale batch and continuous mesophilic anaerobic fermentation experiments. The ratio of the shredded grass with 20. mm or less in length by a commercially available shredder was 93%. The methane production was around 0.2. NL/gVS-grass in the batch experiment. The continuous experiment fed with sewage sludge and shredded grass was stably operated for 81. days. The average methane production was 0.09. NL/gVS-grass when the TS ratio of the sewage sludge and the grass was 10:1. This value was smaller than those of other reports using grass silage, but the grass species in this study were not managed, and the collected grass was just shredded and not ensiled before feeding to the reactor for simple operation. The addition of grass to a digester can improve the carbon/nitrogen ratio, methane production and dewaterability. © 2013 Elsevier Ltd.

Akamatsu F.,Shinshu University | Akamatsu F.,Public Works Research Institute | Toda H.,Shinshu University
Environmental Pollution | Year: 2011

Stable nitrogen isotopic composition (δ15N) of aquatic biota increases with anthropogenic N inputs such as sewage and livestock waste downstream. Increase in δ15N of riparian spiders downstream may reflect the anthropogenic pollution exposure through predation on aquatic insects. A two-source mixing model based on stable carbon isotopic composition showed the greatest dependence on aquatic insects (84%) by horizontal web-building spiders, followed by intermediate (48%) and low (31%) dependence by cursorial and vertical web-building spiders, respectively. The spider body size was negatively correlated with the dietary proportion of aquatic insects and spider δ15N. The aquatic subsidies transported anthropogenic N to smaller riparian spiders downstream. This transport of anthropogenic N was regulated by spider's guild designation and body size. © 2011 Elsevier Ltd. All rights reserved.

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