南沙他国侵占岛礁战略价值及空间格局评价     

闵开付  程亮  周晓  夏南  李宁  李满春 《热带地理》2020,40(4):684-693

从建岛潜力、岛礁辐射能力和岛礁承载能力3个方面选取26个指标,采用主客观综合赋权法确定各因子权重,利用线性加权法获得被越南、菲律宾、马来西亚、文莱等国所侵占的南沙44个岛礁的战略价值,并对结果进行空间插值,分析其空间格局特征。结果表明：1）被马来西亚侵占的弹丸礁、越南侵占的南威岛、以及菲律宾侵占的中业岛,其战略价值位列前3,评价得分分别为100、98.42和97.09。2）岛礁辐射能力空间分布格局呈现“NW—SE条带式”,“最高”和“高”等级的区域由研究区西北延伸至东南,然后向东北、西南两侧递减,辐射能力格局中有2个核心区域和2个次级核心区域。承载能力空间分布格局呈现“横向条带式”,由北向南越来越低,有1个核心区域和2个次级核心区域。建岛潜力空间分布格局有3个核心区域及2个次级核心区域。3）岛礁战略价值空间分布格局有3个核心区域,分布于研究区中部、北部及南部,与越南、菲律宾、马来西亚密切相关的核心区域各有1个。越南侵占岛礁最多且空间分布较广,有2个次级核心区域也与越南密切相关,越占岛礁若进一步建设,将形成多核心协同的战略格局,需密切关注。  相似文献   

Effect of open gap in coastal forest on tsunami run-up—investigations by experiment and numerical simulation     

Nguyen Ba Thuy  Katsutoshi Tanimoto  Norio Tanaka  Kenji Harada  Kosuke Iimura 《Ocean Engineering》2009,36(15-16):1258-1269

The objective of this study is to investigate the effects of an open gap, such as a road, in a coastal forest on tsunami run-up. A numerical model based on two-dimensional nonlinear long-wave equations was developed to account for the effects of drag and turbulence induced shear forces due to the presence of vegetation. Experiments were conducted on a forest simulated with vertical cylinders by changing the gap width. The numerical model was validated in good agreement with the experimental results. The numerical model was then applied to a wide forest of Pandanus odoratissimus, a tree species that is a dominant coastal vegetation on a sand dune in South and Southeast Asia. The effect of vertical stand characteristics of P. odoratissimus with aerial roots was considered on the drag resistance. A straight open gap perpendicular to the shoreline was used to investigate the effect of gap width. As the gap width increases, the flow velocity at the end of the open gap first increases, reaches a maximum, and then decreases, while the run-up height increases monotonously. The maximum velocity in the present condition is 1.7 times the maximum velocity without a coastal forest. The effects of different gap arrangements in the forest on tsunami run-up were also investigated in this paper. The flow velocity at the end of an open gap can be reduced by a staggered arrangement.  相似文献   

Persistent organochlorine residues in sediments from the Chukchi Sea, Bering Sea and Gulf of Alaska   总被引：14，自引：0，他引：14  

Hisato Iwata  Shinsuke Tanabe  Mari Aramoto  Norio Sakai  Ryo Tatsukawa 《Marine pollution bulletin》1994,28(12):746-753

Three surface sediments and two sediment cores were collected from the Gulf of Alaska, Bering Sea and Chukchi Sea, and analysed for persistent organochlorines (OCs). The geographical distributions of OCs showed different patterns according to their physicochemical properties. The concentrations of HCHs and HCB revealed rather uniform distribution, suggesting their more transportable nature in long-range atmospheric transport. On the other hand, DDTs and PCBs were predicted to be less transportable via the atmosphere due to the decreasing trends of residue levels in sediments from south to north. The OC profiles in the sediment core from the Gulf of Alaska which seemed to be preserved without turbation revealed the elevated residue levels from bottom to surface layers. This implies that the aerial inputs of OCs in the cold ocean are still continuing significantly. The accumulation rates of OCs into sediments were rather smaller than the atmospheric inputs, indicating that the residue levels in water bodies are unlikely to decrease rapidly in the near future.  相似文献   

Introduction to the Special Issue of the Symposium on deep-seated landslides and large-scale rock avalanches     

Norio Oyagi  Marino Sorriso-Valvo  Barry Voight 《Engineering Geology》1994,38(3-4):187-188

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Structural and fabric analyses of basal slip zone of the Jin’nosuke-dani landslide, northern central Japan: its application to the slip mechanism of decollement     

Kiichiro Kawamura  Yujiro Ogawa  Norio Oyagi  Tetsuro Kitahara  Ryo Anma 《Landslides》2007,4(4):371-380

We describe in detail the deformation structures and textures of a large-scale landslide body that developed in the Betto-dani Valley in northern central Japan. We studied the shape-preferred orientation of clasts and clay flakes and the development of internal shear planes within the slip zone of the landslide. The slip has an average rate of 5–10 cm/year under the overburden pressure of approximately 1.6 MPa; these values are similar to those of the proto-decollement zone of the Nankai accretionary prism in SW Japan. The anisotropy of magnetic susceptibility of samples obtained from the slip zone reveals that the long axes of clay flakes define an imbricate structure. The slip was due to a long-term periodical creep, which occurs during the thaw seasons with an average slip rate of 0.16–0.32 μm/min. During the creep, the long axes of grains including clay flakes in the slip zone are developed from parallel to perpendicular to the slip direction. The observed textures provide a clue to elucidate the deformation textures and process in the decollement zone of the Nankai prism.  相似文献   

Analysis of Physical and Chemical Parameters for Discrimination of Water Origin in a Hydroelectric Reservoir     

Wagner José Barreto  Ieda Scarminio  Maria Cristina Solci  Dílson Norio Ishikawa  Melissa Tiemi Ogasawara  Sônia Naomi Nomi  Sônia Regina Giancoli Barreto 《洁净——土壤、空气、水》2007,35(3):239-245

Seventeen physical and chemical parameters were obtained from a hydroelectric reservoir located in a tropical region in the south of Brazil. Multivariate Principal Component Analysis (PCA) and Hierarchical Group Analysis (HGA) were used to identify the parameters discriminating the origin of water from the Tibagi and the Primeiro de Maio River, after it has passed the mixing region. The study was conducted during the dry and rainy seasons in July 2002 and February 2003 at three depths and three sampling sites located 0, 5, and 10 km away from the mixing region. The statistical methods showed to be appropriate for identifying the contribution of each tributary in the water mixing site of a complex water system. The most important discriminating parameter was the absorbance relation A(253 nm)/A(203 nm), followed by the concentrations of Fe(III), Mn(III), and Ni(II). An anthropogenic interference was found in the reservoir due to high Ni(II) and orthophosphate concentrations caused by a nearby town sewage discharge. The interference was more important during the dry periods due to the lower dispersion of the pollutants. Urgent initiatives should be taken from the state government to build treatment stations for the wastewater of the small cities around the Capivara hydroelectric reservoir to prevent the drinking water quality from deteriorating.  相似文献   

Analysis of the weightiness of site effects on reinforced concrete (RC) building seismic behaviour: The Adra town example (SE Spain)   总被引：1，自引：0，他引：1  

Manuel Navarro  Francisco Vidal  Takahisa Enomoto  Francisco J. Alcalá  Antonio García‐Jerez  Francisco J. Sánchez  Norio Abeki 《地震工程与结构动力学》2007,36(10):1363-1383

The damage distribution in Adra town (south‐eastern Spain) during the 1993 and 1994 Adra earthquakes (5.0 magnitude), that reached a maximum intensity degree of VII (European Macroseismic Scale (EMS scale)), was concentrated mainly in the south‐east zone of the town and the most relevant damage occurred in reinforced concrete (RC) buildings with four or five storeys. In order to evaluate the influence of ground condition on RC building behaviour, geological, geomorphological and geophysical surveys were carried out, and a detailed map of ground surface structure was obtained. Short‐period microtremor observations were performed in 160 sites on a 100m × 100m dimension grid and Nakamura's method was applied in order to determine a distribution map of soil predominant periods. Shorter predominant periods (0.1–0.3 s) were found in mountainous and neighbouring zones and larger periods (greater than 0.5 s) in thicker Holocene alluvial fans. A relationship T = (0.049 ± 0.001)N, where T is the natural period of swaying motion and N is the number of storeys, has been empirically obtained by using microtremor measurements at the top of 38 RC buildings (ranging from 2 to 9 storeys). 1‐D simulation of strong motion on different soil conditions and for several typical RC buildings were computed, using the acceleration record in Adra town of the 1993 earthquake. It is noteworthy that all the aforementioned results show the influence of site effects in the degree and distribution of observed building damage. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Groundwater-level Anomalies Associated with a Hypothetical Preslip Prior to the Anticipated Tokai Earthquake: Detectability Using the Groundwater Observation Network of the Geological Survey of Japan,AIST     

Norio Matsumoto  Yuichi Kitagawa  Naoji Koizumi 《Pure and Applied Geophysics》2007,164(12):2377-2396

We infer the groundwater-level anomalies associated with a hypothetical preslip prior to the anticipated M 8 Tokai earthquake, and evaluate the detectability of the anomalies using data from seven groundwater wells. We evaluate the detectability of the anomalies under the following assumptions: (1) an Mw 5.5–6.5 aseismic preslip event occurs at the plate boundary in and around the hypothetical focal zone of the Tokai earthquake; (2) the total amount of the strain step at each observation associated with the preslip can be calculated by tensile and shear faulting based on the dislocation model; (3) a normalized strain history associated with the preslip is defined from the results of numerical simulations based on rate- and state-dependent friction laws; and (4) the groundwater-level anomaly prior to the earthquake is proportional to the estimated history of the strain change associated with the preslip. We investigate the detection time of the anomaly at seven wells given an Mw 5.5, 6.0, or 6.5 aseismic preslip at one of the 272 grid points in and around the area of the hypothetical focal zone of the Tokai earthquake. As a result, over the time interval between 1 and 48 hours prior to the hypothetical Tokai earthquake, we are able to detect at each of the seven wells a hypothetical Mw 6.5 preslip at 10–86 of the 272 grid points, an Mw 6 preslip at 0–19 grid points, and an Mw 5.5 preslip at 0–5 grid points.  相似文献   

A search for millimeter wave spectral lines from comet Sugano-Saigusa-Fujikawa (1983e)     

Tetsuo Hasegawa  Masatoshi Ohishi  Masaki Morimoto  Hiroko Suzuki  Norio Kaifu 《Icarus》1984,60(1):211-214

The search for radio spectral lines from Comet Sugano-Saigusa-Fujikawa (1983e) was conducted using the 45-m telescope of Nobeyama Radio Observatory. The frequency ranges of 44.0–46.0 and 47.5–49.5 GHz were surveyed down to $\text{ΔT}{}_{\mathrm{<mtext>A</mtext>}}{}^1\text{(}\text{rms}\text{) = 20–30}\text{mK}$, with a beam size of ～35 arc sec. Upper limits have been established for spectral lines of atomic hydrogen, CS, OCS, SO₂, H₂CO, CH₃OH, HCCCCCN, HCOOCH₃, CH₃OCH₃, and CH₃CH₂CN. The J = 5?4 line from HCCCN in the vibrational ground state possibly has been detected but not confirmed. The suggested total amount of HCCCN in the coma is consistent with the possible picture that HCCCN is the main parent molecule of CN.  相似文献   

以“多规合一”村庄规划为抓手探索乡村振兴困境和对策     

吴方兴  吴铠甫  谢婷 《国土资源导刊(湖南)》2022,19(1):1-5

近年来,我国已初步构建起乡村振兴战略的“四梁八柱”,然而,乡村振兴战略行动计划实施以来,因缺乏科学规划的引领,乡村振兴内生动力不足、成效不显著。旨在厘清“多规合一”村庄规划对实施乡村振兴意义的基础上,分析目前乡村振兴战略在指导乡村发展的过程中存在的难点和堵点,探索以编制“多规合一”村庄规划为抓手,从规划理念、规划内容、规划管控、规划方式、规划队伍、规划支撑、规划指导等方面探索解决问题的途径。  相似文献