Utilizing discriminant function analysis with a geographical information system to model ecological succession spatially

Abstract

A raster/quadtree geographical information system (GIS) was established For a 932 ha natural area in central Missouri. The GIS contained map layers depicting vegetative cover from 1939 to 1982, soils, topographic aspect and distance from a forest seed source. Discriminant function analysis was used to quantify and describe ecological succession on the area during this period. The calibration of discriminant functions is discussed, as are the statistical and spatial validations of the model. It was concluded that this approach provides a useful technique to examine long-term temporal phenomena in a spatial context.     

Fault tectonic analysis of Kii peninsula,Southwest Japan: Preliminary approach to Neogene paleostress sequence near the Nankai subduction zone

The southern part of the Outer Zone of Southwest Japan including the Kii peninsula belongs to the tectonic ‘shadow zone’, where fewer conspicuous active faults and less Quaternary sediments develop than in the Nankai subduction zone and Inner Zone of Southwest Japan. In order to study the paleostress sequence of the Kii peninsula, we analyzed fault‐slip data and tension gashes at pilot sites of Early–Middle Miocene forearc sediments and Late Cretaceous accretionary complex. According to the results, six faulting events are reconstructed in sequence: (i) east–west extension (normal faulting); (ii) east–west compression and north–south extension (strike‐slip faulting); (iii) NNW–SSE compression and ENE–WSW extension (strike‐slip faulting); (iv) northeast–southwest compression and northwest–southeast extension (strike‐slip faulting); (v) WNW–ESE compression (strike‐slip or reverse faulting); and (vi) NNE–SSW extension. The north–south to NNW–SSE trending dyke swarm of Middle Miocene age in the Kii peninsula is thought to be related to Event 3, implying that Event 3 was active at least during the Middle Miocene. Because Event 6 is recognized solely at a site, the overall latest faulting event seems to be Event 5. Assuming that the compression results from the motion of the crust or plate, the compression direction of Event 5 is in good accordance with the present‐day WNW crustal velocity vectors of the Kii peninsula. The stress trajectory map of Southeast Korea and Southwest Japan reveals that the current compression directions of the Kii peninsula correspond to the combinatory stress fields of the Himalayan and Philippine Sea tectonic domains.     

Multiple Tuned Mass Damper Based Vibration Mitigation of Offshore Wind Turbine Considering Soil-Structure Interaction

The dynamics of jacket supported offshore wind turbine (OWT) in earthquake environment is one of the progressing focuses in the renewable energy field. Soil-structure interaction (SSI) is a fundamental principle to analyze stability and safety of the structure. This study focuses on the performance of the multiple tuned mass damper (MTMD) in minimizing the dynamic responses of the structures objected to seismic loads combined with static wind and wave loads. Response surface methodology (RSM) has been applied to design the MTMD parameters. The analyses have been performed under two different boundary conditions: fixed base (without SSI) and flexible base (with SSI). Two vibration modes of the structure have been suppressed by multi-mode vibration control principle in both cases. The effectiveness of the MTMD in reducing the dynamic response of the structure is presented. The dynamic SSI plays an important role in the seismic behavior of the jacket supported OWT, especially resting on the soft soil deposit. Finally, it shows that excluding the SSI effect could be the reason of overestimating the MTMD performance.     

Palaeoecology of a Late Weichselian vertebrate fauna from Nmre Lyngby, Denmark

Investigations at a Late Weichselian freshwater basin in northwestern Jutland, Denmark, yielded a fairly rich assemblage of vertebrate remains, mostly bones and teeth of small mammals. The remains are primarily allochthonous and the bones have been subjected to different taphonomic pathways and agents. AMS ¹⁴C-dates on terrestrial organic remains provided ages of Middle to Late Allerød time. Identifications revealed the first fossil record in Scandinavia of Rana arvalis, Sorex minutus, Ochotona cf. pusilla, Microtus gregalis, Microtus oeconomus , and Sicista cf. betulinu. Spermophilus cf. major and Desmana moschata , previously found only once and twice respectively, were retrieved, and Sorex araneus and Arvicola terrestris were recovered for the first time beyond the Atlantic chronozone. Ecologically, the Nørre Lyngby small mammal fauna can be characterized by its very high and almost equal proportions of boreal forest and steppe elements followed by a relatively high proportion of tundra elements. The fossil species share a modern area of sympatry north of the Caspian Sea from the river Volga in the west to the southern and western slopes of the Urals. If, however, the large Allerød mammals are added, the fauna is without modern analogues. The Nørre Lyngby fauna can be seen as a last expansion of the North European glacial fauna. Provided that an absolute chronology and a differentiated sea-level curve for the area can be established, the Nsrre Lyngby fauna could become important for studies in mammalian dispersal and migration rates.     

Possibility of Solid Hydrometeor Growth Zone Identification Using Radar Spectrum Width

In this study, the correlation between simulated and measured radar velocity spectrum width(σ_v) is investigated. The results show that the dendrites growth zones(DGZs) and needles growth zones(NGZs) mostly contain dendrites(DN) and needles(NE), respectively.Clear σ_v zones(1.1 < σ_v(m s^–1) < 1.3 and 0.3 < σ_v(m s^–1) < 0.7 for the DGZ and NGZ, respectively) could be identified in the case studies(27 and 28 February 2016) n...     

中国海-西太平洋莫霍面深度分布特征及其地质意义

中国海-西太平洋位于欧亚板块、印澳板块和太平洋板块的交汇处,构造运动剧烈,地质情况复杂,是认识板块运动、洋陆相互作用、物质交换和能量传递不可多得的窗口,而莫霍面深度对于研究壳幔结构以及深部动力过程有着重要的意义.本文使用最新的覆盖全球的重力和地形数据,收集了深地震测深、多道地震测深等剖面183条,数字化得到2982个控制点,使用带控制点的三维界面反演方法来约束反演过程,得到中国海-西太平洋莫霍面深度,由莫霍面形态分析可知大洋板块的俯冲和印澳板块与欧亚板块的碰撞对西太平洋边缘海的形成演化有着重要作用.结合地热、岩石圈厚度、地震活动等地质地球物理资料,分析得知研究区内各个海域莫霍深度和地壳性质的变化是处于不同构造演化阶段的表现.并在马里亚纳沟弧盆拟合一条重力2.5维剖面,结果表明热物质上涌导致了马里亚纳海槽处地幔密度减小,马里亚纳海槽以及帕里西维拉海盆到西马里亚纳海岭的下地壳高密度异常是由残留的岩浆岩引起的.     

Numerical Study on Air Turbines with Enhanced Techniques for OWC Wave Energy Conversion

In recent years, the oscillating water column (OWC) wave energy converter, which can capture wave energy from the ocean, has been widely applied all over the world. As the essential part of the OWC system, the impulse and Wells turbines are capable of converting the low pressure pneumatic energy into the mechanical shaft power. As an enhanced technique, the design of endplate or ring attached to the blade tip is investigated numerically in this paper. 3D numerical models based on a CFD-software FLUENT 12.0 are established and validated by the corresponding experimental results from the reports of Setoguchi et al. (2004) and Takao et al. (2001). Then the flow fields and non-dimensional evaluating coefficients are calculated and analyzed under steady conditions. Results show that the efficiency of impulse turbine with ring can reach up to 0.49 when φ=1, which is 4% higher than that in the cases for the endplate-type and the original one. And the ring-type Wells turbine with fixed guide vanes shows the best performance with the maximal efficiency of 0.55, which is 22% higher than that of the original one. In addition, the quasi-steady analysis is used to calculate the mean efficiency and output-work of a wave cycle under sinusoidal flow condition. Taking all together, this study provides support for structural optimization of impulse turbine and Wells turbine in the future.     

Storm-influenced siliciclastic and carbonate ramp deposits, the Lower Ordovician Dumugol Formation, South Korea

The Dumugol Formation (Lower Ordovician) in the southern part of the Baegunsan syncline, South Korea, contains mixed siliciclastic and carbonate ramp deposits. The ramp sediments were frequently influenced by storm events resulting in tempestites of sandstone-mudstone couplets, bioclastic grainstones to packstones, flat-pebble conglomerates, a skeletal lag layer and laminated calcisiltites. All tempestites are characterized by an erosive to sharp base, poor grading and a transitional upper boundary. The difference in lithology of tempestites appears to have been controlled by the nature of substrates and by proximality. For example, laminated calcisiltites have developed on the shallow carbonate ramp, flat-pebble conglomerates are closely associated with nodular limestones on shallow and deep ramps, and thin skeletal lag layers from fossiliferous argillaceous sediments formed in a basinal setting. The stratigraphic succession of the Dumugol Formation represents an initial transgression followed by a regression. The vertical facies change records the transition from a shallow siliciclastic ramp to a deep carbonate ramp, to a basin, shallowing to a deep carbonate ramp, and to a shallow carbonate ramp. Storm effects are mostly well preserved in shallow to deep ramp deposits.     

Effects of Wind Fences on the Wind Environment around Jang Bogo Antarctic Research Station

This study investigated the flow characteristics altered by Jang Bogo Antarctic Research Station using computational fluid dynamics(CFD) modeling. The topography and buildings around Jang Bogo Station were constructed with computeraided-design data in the CFD model domain. We simulated 16 cases with different inflow directions, and compared the flow characteristics with and without Jang Bogo Station for each inflow direction. The wind data recorded by the site's automatic weather station(AWS) were used for comparison. Wind rose analysis showed that the wind speed and direction after the construction of Jang Bogo Station were quite different from those before construction. We also investigated how virtual wind fences would modify the flow patterns, changing the distance of the fence from the station as well as the porosity of the fence. For westerly inflows, when the AWS was downwind of Jang Bogo Station, the decrease in wind speed was maximized(-81% for west-northwesterly). The wind speed reduction was also greater as the distance of the fence was closer to Jang Bogo Station. With the same distance, the fence with medium porosity(25%–33%) maximized the wind speed reduction.These results suggest that the location and material of the wind fence should be selected carefully, or AWS data should be interpreted cautiously, for particular prevailing wind directions.     

High-frequency acoustic backscattering characteristics for acoustic detection of the red tide species Akashiwo sanguinea and Alexandrium affine

Harmful algal blooms(HABs),caused by the overgrowth of certain phytoplankton species,have negative effects on marine environments and coastal fisheries.In addition to cell-counting methods using phytoplankton nets,a hydroacoustic technique based on acoustic backscattering has been proposed for the detection of phytoplankton blooms.However,little is known of the acoustic properties of HAB species.In this study,as essential data to support this technique,we measured the acoustic properties of two HAB species,Akashiwo sanguinea and Alexandrium affine,which occur in the South Sea off the coast of Korea.Due to the small size of the target,we used ultrasound for the measurements.Experiments were conducted under laboratory and field conditions.In the laboratory experiment,the acoustic signal received from each species was directly proportional to the cell abundance.We derived a relationship between the cell abundance and acoustic signal received for each species.The measured signals were compared to predictions of a fluid sphere scattering model.When A.sanguinea blooms appeared at an abundance greater than 3 500 cells/mL,the acoustic signals varied with cell abundance,showing a good correlation.These results confirm that acoustic measurements can be used to detect HAB species.