A comparison of neighbourhood relations based on ordinary Delaunay diagrams and area Delaunay diagrams: an application to define the neighbourhood relations of buildings     

Hiroyuki Usui  Akihiro Teraki  Kei-ichi Okunuki  Toshiaki Satoh 《International journal of geographical information science》2020,34(11):2177-2203

ABSTRACT

The aim of this article is to describe a convenient but robust method for defining neighbourhood relations among buildings based on ordinary Delaunay diagrams (ODDs) and area Delaunay diagrams (ADDs). ODDs and ADDs are defined as a set of edges connecting the generators of adjacent ordinary Voronoi cells (points representing centroids of building polygons) and a set of edges connecting two centroids of building polygons, which are the generators of adjacent area Voronoi cells, respectively. Although ADDs are more robust than ODDs, computation time of ODDs is shorter than that of ADDs (the order of their computation time complexity is O(nlogn)). If ODDs can approximate ADDs with a certain degree of accuracy, the former can be used as an alternative. Therefore, we computed the ratio of the number of ADD edges to that of ODD edges overlapping ADDs at building and regional scales. The results indicate that: (1) for approximately 60% of all buildings, ODDs can exactly overlap ADDs with extra ODD edges; (2) at a regional scale, ODDs can overlap approximately 90% of ADDs with 10% extra ODD edges; and (3) focusing on judging errors, although ADDs are more accurate than ODDs, the difference is only approximately 1%.  相似文献   

Re-Os isotope systematics and fractionation of siderophile elements in metal phases from CBa chondrites          下载免费PDF全文

Nao Nakanishi  Tetsuya Yokoyama  Satoki Okabayashi  Tomohiro Usui  Hikaru Iwamori 《Meteoritics & planetary science》2018,53(5):1051-1065

We report Os isotope compositions of metal grains in two CB_a chondrites (Bencubbin and Gujba) determined using a micromilling sampling coupled with thermal ionization mass spectrometry, together with the abundances of major and trace siderophile elements obtained by electron probe microanalysis and femtosecond laser ablation inductively coupled plasma–mass spectrometry. The CB_a metal grains presented ¹⁸⁷Os/¹⁸⁸Os ratios akin to carbonaceous chondrites with limited variations (0.1257–0.1270). Most of the CB_a metal grains were scattered along a ¹⁸⁷Re-¹⁸⁷Os reference isochron of IIIAB iron meteorites, indicating that the CB_a metals experienced limited Re-Os fractionation at the time of their formation. The Re/Os ratios of sampling spots for the CB_a metals, recast from the observed ¹⁸⁷Os/¹⁸⁸Os ratios, had a positive correlation with their Os/Ir ratios. In addition, the metal grains showed a positive correlation in a Pd/Fe versus Ni/Fe diagram. These correlations suggest that the CB_a metal grains have formed via equilibrium condensation or evaporation from a gaseous reservoir at ~10⁻⁴ bar with enhanced metal abundances. Compared to the Bencubbin metals, the Gujba metals are characterized by having systematically lower Pd/Fe and Ni/Fe ratios that span subchondritic values. Such a difference was most likely induced by the compositionally heterogeneous impact plume from which the metals were condensed.  相似文献   

Development of a 2-km resolution ocean model covering the coastal seas around Japan for operational application     

Sakamoto  Kei  Tsujino  Hiroyuki  Nakano  Hideyuki  Urakawa  Shogo  Toyoda  Takahiro  Hirose  Nariaki  Usui  Norihisa  Yamanaka  Goro 《Ocean Dynamics》2019,69(10):1181-1202

Ocean Dynamics - In order to expand the coastal ocean monitoring and forecasting system of the Japan Meteorological Agency from the Seto Inland Sea to the entire coastal seas of Japan, a 2-km...  相似文献   

Spatial partitioning between species of the phytoplankton-feeding guild on an estuarine intertidal sand flat and its implication on habitat carrying capacity     

Akio Tamaki  Ayumi Nakaoka  Hideki Maekawa  Fumihiko Yamada 《Estuarine, Coastal and Shelf Science》2008,78(4):727-738

The fishery yield of Manila clams, Ruditapes philippinarum, increased considerably in the 1970s but has decreased rapidly since the middle 1980s on extensive intertidal sand flats in Ariake Sound (Kyushu, Japan). A survey conducted in 2004 on a 3.4-km² sand flat located in the central part of the Sound (Shirakawa sand flat) revealed four dominant species: two thalassinidean shrimps (Upogebia major and Nihonotrypaea japonica), which are deep-reaching burrow dwellers with strong bioturbation activities, and two bivalves (Mactra veneriformis and R. philippinarum). All four species belong to a phytoplankton (diatom)-feeding guild. In the late 1970s, the Manila clam population prevailed in high densities over the entire sand flat, whereas its distribution was restricted to the lowest quarter of the shore in 2004. In contrast, the population sizes and zones of occurrence of the other phytoplankton feeders have expanded in the absence of R. philippinarum, perhaps an indication of competitive release. After establishment, effects of the thalassinidean shrimps on sediment stability appear to have further reduced clam abundances. Across the sand flat in 2004, wet weight population biomass estimates for N. japonica, U. major, M. veneriformis, and R. philippinarum (whole body for shrimps and soft tissue for bivalves) were 304, 111, 378, and 234 tonnes, respectively. Based on Manila clam fishery yield records from Shirakawa, the carrying capacity of the Shirakawa sand flat in the late 1970s was estimated to be two times greater than the sum value for the whole phytoplankton-feeding guild in 2004. It is hypothesized that (1) the amount of phytoplankton determines the carrying capacity for the benthic community on the Shirakawa sand flat, with both phytoplankton and benthic biomass at maxima in the late 1970s, and (2) the subsequent increases in competition for space have caused further declines in the Manila clam population biomass to approximately one-eighth of its past value.  相似文献   

Molecular-scale mechanisms of distribution and isotopic fractionation of molybdenum between seawater and ferromanganese oxides   总被引：1，自引：0，他引：1  

Teruhiko Kashiwabara  Yoshio Takahashi  Akira Usui 《Geochimica et cosmochimica acta》2011,75(19):5762-5784

The distribution of Mo between seawater and marine ferromanganese oxides has great impacts on concentration and isotopic composition of Mo in modern oxic seawater. To reveal the adsorption chemistry of Mo to ferromanganese oxides, we performed (i) detailed structural analyses of Mo surface complexes on δ-MnO₂, ferrihydrite, and hydrogenetic ferromanganese oxides by L₃- and K-edge XAFS, and (ii) adsorption experiments of Mo to δ-MnO₂ and ferrihydrite over a wide range of pHs, ionic strengths, and Mo concentrations. XAFS analyses revealed that Mo forms distorted octahedral (Oh) inner-sphere complexes on δ-MnO₂ whereas it forms a tetrahedral (Td) outer-sphere complex on ferrihydrite. In the hydrogenetic ferromanganese oxides, the dominant host phase of Mo was revealed to be δ-MnO₂. These structural information are consistent with the macroscopic behaviors of Mo in adsorption experiments, and Mo concentration in modern oxic seawater can be explained by the equilibrium adsorption reaction on δ-MnO₂. In addition, the large isotopic fractionation of Mo between seawater and ferromanganese oxides detected in previous studies can be explained by the structural difference between and adsorbed species on the δ-MnO₂ phase in ferromanganese oxides. In contrast, smaller fractionation of Mo isotopes on ferrihydrite is due to little change in the Mo local structures during its adsorption to ferrihydrite.The structures of Mo species adsorbed on crystalline Fe (oxyhydr)oxides, goethite, and hematite were also investigated at pH 8 and I = 0.70 M (NaNO₃). Our XAFS analyses revealed that Mo forms inner-sphere complexes on both minerals: Td edge-sharing (46%) and Oh double corner-sharing (54%) for goethite, and Td double corner-sharing (14%) and Oh edge-sharing (86%) for hematite. These structural information, combined with those for amorphous ferrihydrite and δ-MnO₂, show the excellent correlation with the magnitude of adsorptive isotopic fractionation of Mo reported in previous studies: the proportion of Oh species or their magnitude of distortion in Mo surface complexes become larger in the order of ferrihydrite < goethite < hematite < δ-MnO₂, a trend identical to the magnitude of isotopic fractionation.Based on the comparison with previous reports for Mo surface species on various oxides, the chemical factors that affect Mo surface complex structures were also discussed. The hydrolysis constant of cation in oxides, log K_OH (or the acidity of the oxide surfaces, PZC) is well correlated with the mode of attachment (inner- or outer-sphere) of Mo surface complexes. Furthermore, the symmetric change in Mo species from Td to Oh is suggested to be driven by the formation of inner-sphere complexes on specific sites of the oxide surfaces.  相似文献   

Field survey of the 1994 Mindoro Island,Philippines tsunami   总被引：2，自引：0，他引：2  

Fumihiko Imamura  Costas E. Synolakis  Edison Gica  Vasily Titov  Eddie Listanco  Ho Jun Lee 《Pure and Applied Geophysics》1995,144(3-4):875-890

This is a report of the field survey of the November 15, 1994 Mindoro Island, Philippines, tsunami generated by an earthquake (M=7.0) with a strike-slip motion. We will report runup heights from 54 locations on Luzon, Mindoro and other smaller islands in the Cape Verde passage between Mindoro and Luzon. Most of the damage was concentrated along the northern coast of Mindoro. Runup height distribution ranged 3–4 m at the most severely damaged areas and 2–4 in neighboring areas. The tsunami-affected area was limited to within 10 km of the epicenter. The largest recorded runup value of 7.3 m was measured on the southwestern coast of Baco Island while a runup of 6.1 m was detected on its northern coastline. The earthquake and tsunami killed 62 people, injured 248 and destroyed 800 houses. As observed in other recent tsunami disasters, most of the casualties were children. Nearly all eyewitnesses interviewed described the first wave as a leading-depression wave. Eyewitnesses reported that the main direction of tsunami propagation was SW in Subaang Bay, SE in Wawa and Calapan, NE on Baco Island and N on Verde Island, suggesting that the tsunami source area was in the southern Pass of Verde Island and that the wave propagated rapidly in all directions. The fault plane extended offshore to the N of Mindoro Island, with its rupture originating S of Verde Island and propagating almost directly south to the inland of Mindoro, thereby accounting for the relatively limited damage area observed on the N of Mindoro.  相似文献   

Field survey of the East Java earthquake and tsunami of June 3, 1994     

Yoshinobu Tsuji  Fumihiko Imamura  Hideo Matsutomi  Costas E. Synolakis  Puspito T. Nanang  Jumadi  Satoshi Harada  Se Sub Han  Ken'ichi Arai  Benjamin Cook 《Pure and Applied Geophysics》1995,144(3-4):839-854

A field survey of the June 3, 1994 East Java earthquake tsunami was conducted within three weeks, and the distributions of the seismic intensities, tsunami heights, and human and house damages were surveyed. The seismic intensities on the south coasts of Java and Bali Islands were small for an earthquake with magnitudeM 7.6. The earthquake caused no land damage. About 40 minutes after the main shock, a huge tsunami attacked the coasts, several villages in East Java Province were damaged severely, and 223 persons perished. At Pancer Village about 70 percent of the houses were swept away and 121 persons were killed by the tsunami. The relationship between tsunami heights and distances from the source shows that the Hatori's tsunami magnitude wasm=3, which seems to be larger for the earthquake magnitude. But we should not consider this an extraordinary event because it was pointed out byHatori (1994) that the magnitudes of tsunamis in the Indonesia-Philippine region generally exceed 1–2 grade larger than those of other regions.  相似文献   

Source models for the 1993 Hokkaido Nansei-Oki earthquake tsunami   总被引：1，自引：0，他引：1  

Tomoyuki Takahashi  Takeyuki Takahashi  Nobuo Shuto  Fumihiko Imamura  Modesto Ortiz 《Pure and Applied Geophysics》1995,144(3-4):747-767

A source model for the 1993 Hokkaido Nansei-Oki tsunami must satisfy certain conditions. Such conditions are presented in this paper, and two methods are used to determine the best source model for this event. A trial-and-error method selects DCRC-17a as the best among 24 different models. This model has three fault planes dipping westward. To reproduce well the tide gauge records at two locations, an inversion analysis is used to modify the dislocation of DCRC-17a.  相似文献   

Building damage characteristics based on surveyed data and fragility curves of the 2011 Great East Japan tsunami   总被引：4，自引：2，他引：2  

Anawat Suppasri  Erick Mas  Ingrid Charvet  Rashmin Gunasekera  Kentaro Imai  Yo Fukutani  Yoshi Abe  Fumihiko Imamura 《Natural Hazards》2013,66(2):319-341

A large amount of buildings was damaged or destroyed by the 2011 Great East Japan tsunami. Numerous field surveys were conducted in order to collect the tsunami inundation extents and building damage data in the affected areas. Therefore, this event provides us with one of the most complete data set among tsunami events in history. In this study, fragility functions are derived using data provided by the Ministry of Land, Infrastructure and Transportation of Japan, with more than 250,000 structures surveyed. The set of data has details on damage level, structural material, number of stories per building and location (town). This information is crucial to the understanding of the causes of building damage, as differences in structural characteristics and building location can be taken into account in the damage probability analysis. Using least squares regression, different sets of fragility curves are derived to demonstrate the influence of structural material, number of stories and coastal topography on building damage levels. The results show a better resistant performance of reinforced concrete and steel buildings over wood or masonry buildings. Also, buildings taller than two stories were confirmed to be much stronger than the buildings of one or two stories. The damage characteristic due to the coastal topography based on limited number of data in town locations is also shortly discussed here. At the same tsunami inundation depth, buildings along the Sanriku ria coast were much greater damaged than buildings from the plain coast in Sendai. The difference in damage states can be explained by the faster flow velocities in the ria coast at the same inundation depth. These findings are key to support better future building damage assessments, land use management and disaster planning.  相似文献   

Long-term variability of the Kuroshio path south of Japan     

Norihisa Usui  Hiroyuki Tsujino  Hideyuki Nakano  Satoshi Matsumoto 《Journal of Oceanography》2013,69(6):647-670

This study investigates the long-term variability of the Kuroshio path south of Japan. Sensitivity experiments using a data-assimilative model suggest that the duration of the large meander (LM) strongly depends on the Kuroshio transport; specifically, low transport leads to a long duration of the LM. Actually, we find a good correlation between the duration of the past LMs and the Sverdrup transport estimated by a wind-driven linear baroclinic vorticity model. Then we explore favorable conditions for the LM and find a close relationship between the Kuroshio Extension (KE) state and the LM. That is, a precondition for the LM that the Kuroshio path on the Izu Ridge is fixed at a deep channel located around 34°N is achieved during a stable KE state. In addition, westward propagating signals with negative anomalies in the Kuroshio region and high sea-surface height (SSH) state east of Taiwan are key for generation of a small meander southeast of Kyushu that triggers a subsequent LM. The signals related to the above conditions change the upstream Kuroshio transport and velocity, which are consistent with features indicated by the former observational studies. Using reanalysis data, we construct long-time series of indices for the three conditions, which explain well the past LMs. The indices suggest that long-term non-LM states around 1970 and in the 1990s were attributed to a low-SSH state east of Taiwan and an unstable KE state, respectively.  相似文献