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Ling H.I.,Columbia University | Leshchinsky D.,University of Delaware | Mohri Y.,Japan National Institute of Rural Engineering of Japan | Wang J.-P.,Hong Kong University of Science and Technology
Journal of Geotechnical and Geoenvironmental Engineering | Year: 2012

This paper reports on the seismic performance of three geosynthetic-reinforced segmental retaining wall systems backfilled witha silty sand mixture, using a shaking table excited by 1995 Kobe earthquake loadings. The preparation of the backfill mixture and its properties, the tested wall configurations, the reinforcement layouts and instrumentations, and the observed wall performance are described. Visual observations and test results indicate that walls having 0.4-m vertical reinforcement spacing, backfilled with soil containing a large percentage of fines, performed better than those having good-quality sandy soil under otherwise identical conditions. Vertical spacing of 0.8 m with removal of interlocking facing blocks in one of the walls did not lead to global collapse under repeated applications of the Kobe earthquake loadings. Only localized shear failure behind the top block layer was observed as thetop facing blocks tended to topple. The good performance was attributable to apparent cohesion in the soil mixture stemming from soil matrix suction and true cohesion. Because this apparent cohesion is affected by the moisture content, its existence must be ensured by providing proper drainage to prevent seepage into the backfill. Considering the risk associated with the use of apparent cohesion, its exclusion from design is recommended. © 2012 American Society of Civil Engineers.

Ito H.,Japan Central Research Institute of Electric Power Industry | Nanayama F.,Geological Survey of Japan | Nakazato H.,Japan National Institute of Rural Engineering of Japan
Quaternary Geochronology | Year: 2016

Zircon U-Pb dating using LA-ICP-MS was applied to six Quaternary tephras in Boso Peninsula, central Japan: J1, Ks4, Ks5, Ks10, Ks11, and Ch2 in descending order. Accurate age determination of these tephras is of critical importance because they are widespread tephras in Japan and also relevant to a candidate site for the global boundary stratotype section and point of the early-middle Pleistocene boundary. Twenty grains were dated for each tephra and the following results were obtained. The J1 tephra had only 5 grains that yielded <2 Ma. The obtained age was ∼0.2 m.y. older than the stratigraphic age. No Quaternary ages were obtained from the Ks4 tephra. The Ks5 and Ks10 tephras had 10-12 grains that were ∼0.1-0.3 m.y. older than the stratigraphic age. The Ks11 tephra had 14 grains that yielded a weighted mean age of 0.52 ± 0.04 Ma (error reported as 95% confidence level), which was in agreement with the stratigraphic age. The Ch2 tephra had 16 grains that yielded a weighted mean age of 0.61 ± 0.02 Ma, which was also in agreement with the stratigraphic age. The good agreement between zircon U-Pb ages and the stratigraphy for Ks11 and Ch2 tephras validates the reliability of the established stratigraphy and our dating approach. The other tephras that yielded ∼0.1-0.3 m.y. older ages than the stratigraphy may indicate that the analyzed zircons were antecrysts that crystallized before eruption or they were detrital zircons incorporated during deposition. © 2016 Elsevier B.V.

Okazaki H.,Chiba Institute of Science | Nakazato H.,Japan National Institute of Rural Engineering of Japan | Kwak Y.,Public Works Research Institute PWRI
Sedimentary Geology | Year: 2013

Ground penetrating radar (GPR) offers a fast and efficient method for visualizing three-dimensional (3D) images of shallow subsurface structures. We investigated the application of GPR to nondestructive imaging of deposits formed in a small experimental flume using a high-frequency GPR antenna. The GPR measurements, made with a 1.6. GHz antenna, were conducted on flume models of sandy fluvial systems. We conducted two experiments, one to reveal the penetration depth and resolution of the GPR antenna and to reconstruct the 3D architecture of fluvial deposits created in a flume, and the other to examine the characteristics of reflection boundaries. The experimental materials were mainly loamy soil. The first experiment showed that a 1.6 GHz antenna was suited to laboratory use, offering a depth resolution of 2-3 cm in full penetration of a bed 15-24 cm thick. GPR scanning yielded an accurate reconstruction of the 3D architecture of a fluvial channel using magnetite marker beds. The second experiment also successfully imaged a 3D architecture using quartz sand instead of magnetite, and loamy soil, which have different relative permittivities. This research shows that GPR is a feasible technique for 3D analysis of experimental flume deposits. © 2013 Elsevier B.V.

Nakata N.,Colorado School of Mines | Snieder R.,Colorado School of Mines | Kuroda S.,Japan National Institute of Rural Engineering of Japan | Ito S.,Suncoh Consultants Co. | And 2 more authors.
Bulletin of the Seismological Society of America | Year: 2013

For health monitoring of a building, we need to separate the response of the building to an earthquake from the imprint of soil-structure coupling and from wave propagation below the base of the building. Seismic interferometry based on deconvolution, where we deconvolve the wave fields recorded at different floors, is a technique to extract this building response and thus estimate velocity of the wave that propagates inside the building. Deconvolution interferometry also allows us to estimate the damping factor of the building. Compared with other interferometry techniques, such as cross-correlation and cross-coherence interferometry, deconvolution interferometry is the most suitable technique to monitor a building using earthquake records. For deconvolution interferometry, we deconvolve the wave fields recorded at all levels with the waves recorded at a target receiver inside the building. This receiver behaves as a virtual source, and we retrieve the response of a cut-off building, a short building that is cut off at the virtual source. Because the cut-off building is independent from the structure below the virtual source, the technique might be useful for estimating local structure and local damage. We apply deconvolution interferometry to 17 earthquakes recorded during two weeks at a building in Fukushima, Japan, and estimate time-lapse changes in velocity and normal-mode frequency. As shown in a previous study, the change in velocity correlates with the change in normal-mode frequency. We compute the velocities from both traveling waves and the fundamental mode using coda-wave interferometry. These velocities have a negative correlation with the maximum acceleration of the observed earthquake records.

Kunimitsu Y.,Japan National Institute of Rural Engineering of Japan
Japan Agricultural Research Quarterly | Year: 2015

Future climate change will affect rice production, but whether these changes will be beneficial or detrimental is unclear. The present study evaluates the effect of climate change on Japanese rice production, rice price, agricultural income, and regional economies by using a recursive-dynamic regional computable general equilibrium (CGE) model, which is associated with crop-growth and crop-quality models. Simulation results demonstrate that future climate change will increase overall Japanese rice production nationwide, but that the price of rice will decrease. As a result, agricultural income will decrease, despite increased production in northern and eastern Japan, such as Hokkaido, Tohoku, and Kanto (including Niigata prefecture). Climate change will not benefit rice farmers in these regions. However, the western region will benefit, despite the decrease in production, and the consumer surplus in most regions will increase. This happens because rice demand is inelastic and an increase in production results in a serious decline in price, which more than offsets the effects of climate change on production. As such, the impacts of climate change are complicated and differ by region, so a CGE model can provide useful information to consider policy countermeasures.

Jang H.,Pukyong National University | Kuroda S.,Japan National Institute of Rural Engineering of Japan | Kim H.J.,Pukyong National University
IEEE Geoscience and Remote Sensing Letters | Year: 2011

Cross-borehole ground-penetrating radar (GPR) has been widely used to characterize the shallow subsurface and to monitor hydrogeologic processes. To investigate an infiltration process in the vadose zone, an artificial groundwater infiltration test was conducted in Nagaoka, Japan. Time-lapse cross-borehole GPR data were collected using zero-offset profiling (ZOP) mode. The infiltration process was observed as a variation of GPR traveltimes, which can be transformed into a dielectric constant, and further converted to volumetric water content. A standard ZOP analysis, for which all first arrivals are assumed to be direct waves, results in an underestimation of the dielectric constant because of the existence of critically refracted waves. This letter presents an efficient algorithm using the maximum first-cycle amplitude to approximately determine the traveltime of direct arrival, deriving a dielectric constant model more accurately than the standard ZOP analysis from ZOP data. Tests on synthetic and real field data show that the proposed approach is effective in building accurate water content profile without iterative calculations as in the standard ZOP analysis. © 2006 IEEE.

Jang H.,Pukyong National University | Kuroda S.,Japan National Institute of Rural Engineering of Japan | Kim H.J.,Pukyong National University
IEEE Transactions on Geoscience and Remote Sensing | Year: 2011

An artificial groundwater infiltration experiment was conducted in Nagaoka city in Japan, and time-lapse cross-borehole ground-penetrating radar (GPR) data were collected to monitor the infiltration process in the vadose zone using zero-offset profiling (ZOP) mode. The downward migration of induced water was observed as a variation of GPR travel times, which can be transformed into dielectric constant and further converted to volumetric water content. In this paper, we present an effective approach to extract accurate information about the hydrogeologic process in the vadose zone from ZOP data. This approach is based on a least squares inversion method using singular-value decomposition, in which a finite-difference time-domain forward modeling is used for computing electromagnetic wave fields on 2-D cylindrical coordinates. The inversion approach is validated using a synthetic example and applied to the field data. We can successfully estimate the variation of soil water content during infiltration in the Nagaoka site from the reconstructed dielectric constant models. The inversion results show that the saturation information is useful to assess hydrogeologic properties of the test soil zone. © 2011 IEEE.

Kunimitsu Y.,Japan National Institute of Rural Engineering of Japan
WIT Transactions on Ecology and the Environment | Year: 2011

Agricultural production depends heavily on climate conditions; therefore, climatic uncertainty caused by global warming represents a significant threat not only to agriculture but also to entire economies. Furthermore, the drastic budget cuts after 2001 in Japan have reduced public capital stock and have placed the production capacities of various industries in jeopardy. This highlights the need for asset management to prolong the structural integrity of facilities. The present study uses the recursive dynamic computable general equilibrium (CGE) model to evaluate asset management measures (namely, those focusing on reinforcing old facilities) in the context of climatic uncertainty. Simulation results showed that the uncertainty of production induced by climate change is amplified through the market mechanism. The variation in the total production was much wider than the variation in agricultural production originally affected by the climate change. The public capital stock maintained by the asset management measures can ease such uncertainty. Therefore, asset management policy, which makes the deficit minimal leeway for increasing public investment, is critical in Japan. The dynamic CGE model can also measure such long-term comprehensive effects and is useful for policy analysis. © 2011 WIT Press.

Kunimitsu Y.,Japan National Institute of Rural Engineering of Japan
Studies in Regional Science | Year: 2015

Bioethanol can reduce CO2 emissions and improve domestic production by replacing gasoline consumption. However, bioethanol competes with food consumption, if it is produced from the edible parts of agricultural products. This study aims to evaluate the pros and cons of bioethanol in the Vietnamese economy by the computable general equilibrium (CGE) model. The simulation results demonstrate the following points. First, a policy that replaces the fixed rate of bioethanol in gasoline brings about reductions in long-run electricity production in addition to direct reduction of petroleum consumption. Moreover, the import of petroleum products, highly dependent on imports at present, can be reduced, and a decrease in imports transfers to domestic production and consequently the self-sufficient rate of energy is raised. Hence, this policy can cut CO2 emissions by 0.7-3.0% more than without the policy. Second, the introduction of bioethanol, produced by first generation technology or by secondgeneration technology with technological progress, increases total income and raises GDP by 0.19% at most. The effects of second-generation bio-ethanol production are higher than for first generation technology because of the high added value of second generation technology. However, second-generation production with the present technology may decrease gross domestic products, because production costs are too high to produce a profit. A government subsidy for bio-ethanol production may cause domestic savings to decline and decrease private investment through crowding-out effects. Although first-generation bio-ethanol production increases competition with food consumption, second-generation bio-ethanol production can avoid competition with food consumption. Hence, policy makers should consider different pathways to affect the national economy and should support technological improvements. Third, the environmental effects of the bio-ethanol introduction policy are lower than the direct effects of CO2 emissions from gasoline consumption reduced by this policy, because this policy stimulates domestic production. In addition to the economic effects, situations in which the economic growth accelerates CO2 emissions can be avoided, as long as a policy that replaces the fixed rate of gasoline consumption is continued., The CGE model is a useful policy tool to show the above complicated effects. © 2015, Japan Section of the Regional Science Association International. All Rights Reserved.

Ganaha-Kikumura T.,Japan National Institute of Rural Engineering of Japan | Kijima K.,Japan National Institute of Rural Engineering of Japan
Applied Entomology and Zoology | Year: 2016

The development, reproduction, and population growth of Thrips nigropilosus Uzel (Thysanoptera: Thripidae), reared on leaves of Chrysanthemummorifolium Ramat (Asteraceae), were studied at seven different constant temperatures. Temperature and development rate of T. nigropilosus from egg to adult were linearly related between 15 and 25 °C, allowing the calculation of a lower threshold of 9.26 °C and a thermal constant of 238.1 degree-days. At 35 °C, eggs failed to hatch and larvae did not develop into adults. Adult longevity decreased with increasing temperature between 15 and 35 °C and females lived longer than males. Mean fecundity was highest at 30 °C, with 42.4 eggs per female. The intrinsic rate of natural increase was highest at 30 °C 0.173. During the late summer to spring, which is the main cultivation season for chrysanthemum in Okinawa, a maximum of 11 generations of T. nigropilosus could occur according to our calculations based on meteorological data from 2015 to 2016. © 2016, The Japanese Society of Applied Entomology and Zoology.

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