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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. Source

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. Source

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. Source

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. Source

Abe J.,Japan National Agricultural Research Center | Ganaha-Kikumura T.,Japan National Institute of Rural Engineering of Japan | Yukawa J.,Kyushu University
Applied Entomology and Zoology | Year: 2011

The distribution records of Feltiellaacarisuga (Vallot) (Diptera: Cecidomyiidae) in Japan were previously based only on the collecting data of Feltiella sp. from Kagoshima in 1971. We identified acarivorous gall midges collected from various localities in Japan as F. acarisuga and found that it is widely distributed in Japan from Hokkaido to Okinawa. A supplementary description to that made by Gagné in 1995 is provided, together with illustrations of the male fifth flagellomere, male genitalia, pupa, and pupal frons. We also provide information on mites on which it preys and ecological traits of F. acarisuga and devote a brief discussion to its use as a biological control agent. We newly confirm that F. acarisuga fed on Acaphylla theavagrans Kadono (Acarina: Eriophyoidea) in addition to tetranychid mites that were recorded earlier. For the convenience of applied entomologists, differences between larvae of F. acarisuga and those of other free-living cecidomyiids that may sometimes be present on the same leaf are briefly explained. © 2011 The Japanese Society of Applied Entomology and Zoology. Source

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