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1.
A problem of locating and comprehensively investigating ocean areas that exercise a significant influence over the migration
dynamics of fishing ranks among important problems of fisheries oceanology. Among all the environment factors affecting various
fishery situations, factors should be chosen that are constantly logged on large water areas for a long time comparable with
fishery observation time. As described in a number of works, the most suitable information for these purposes is data on the
distribution of surface temperature fields.
The problem of locating discriminative areas can then be stated as follows. For a particular fishery situation (e.g., for
the period of maximum catch in fishing season), temperature values or thermostructural features should be singled out that
are suitable to define the situation, using hydrological charts of surface temperature fields. Correlating the feature with
the areas where they were observed, we will obtain discriminative areas.
The important problem is then to develop techniques and means for algorithmically identifying areas. This relates to a vast
volume of information and complex structure.
Logical-mathematical models of locating discriminative areas are being developed at the Pacific Oceanological Institute for
some years. These models are to be for forecasting fishery situations in the NW Pacific. Techniques for representing isotherm
fields in a computer have been developed. Formal operations of comparing the fields have been proposed which aid in distinguishing
significant differences in their structure. A software for analyzing isotherm fields has been developed based on threshold
logic models.
This approach allows one not only to identify discriminative areas for relatively stable fishery situations but also to trace
their dynamics. This has been achieved due to multiple-alternative computations and the presentations of data obtained in
the form suitable for their interpretation. Some components of proposed models have been used in the system of short-term
forecasting saira and sardine fishery in the South-Kuril area. 相似文献
2.
Phillip H. Shelley 《Geoarchaeology》1993,8(1):59-72
The methods and techniques presented provide a means for evaluating raw material characteristics in those situations where secondary deposits of lithic materials were exploited for stone tool production. Those aspects of secondary deposits measured or estimated include size, form, roundness, crystallinity, homogeneity, and raw material frequency. A comparison and discussion of two sampled areas in eastern New Mexico demonstrate how these procedures can be used to elucidate meaningful archaeological information. © 1993 John Wiley & Sons, Inc. 相似文献
3.
通过对北京山区历史泥石流降雨资料的分析,根据有雨量站和无雨量站的泥石流易发区的资料情况,分别建立了不同前期雨量的预报模型,并根据预报模型初步建立了不同前期雨量前提条件下的黄,橙,红三色预报模式。 相似文献
4.
基于易滑地质结构与多源数据差异的岩溶山区大型崩滑灾害识别研究 总被引：1，自引：0，他引：1
岩溶山区地质环境复杂且脆弱,重特大崩滑地质灾害时有发生。如果对岩溶山区的地质环境认知不准,将直接导致对灾害识别能力不足。文章围绕岩溶山区裸露型岩溶陡崖、复合岩组型斜坡以及非裸露型岩溶斜坡3类基本易滑地质结构差异,探讨多源数据条件下更具适用性的识别探测方法。对于空间影响面积小的厚层岩溶陡崖结构,星-地组合识别方法更加适用,基于GNSS的识别探测方式可在获得动态变形趋势基础上,对可能发生的失稳模式进行初步预判,同时可对InSAR解译的地表位移进行矢量化校正,有利于提高对具有相同或相近SAR数据条件地区的灾害识别程度。对于具有较大空间影响面积的斜坡区域,可优先选用基于InSAR的遥感技术来获取地表变形结果,对于有致灾风险的大变形区还可结合易滑地质结构及外部影响因素对其可能失稳模式进行预判或反演分析。任何灾害识别方式都有其局限性,在实践中可根据不同地质结构特征与灾害类型特点,通过多源、多维度监测来构建综合识别体系,探索更具适用性的识别探测与数据分析新思路。 相似文献
5.
The spatial–temporal patterns of cloud-to-ground (CG) lightning covering the period 2010–2015 over the northwest Iberian Peninsula were investigated. The analysis conducted employed three main methods: the circulation weather types developed by Jenkinson and Collison, the fit of a generalized additive model (GAM) for geographic variables, and the use of a concentration index for the ratio of lightning strikes and thunderstorm days. The main activity in the summer months can be attributed to situations with eastern or anticyclonic flow due to convection by insolation. In winter, lightning proves to have a frontal origin and is mainly associated with western or cyclonic flow situations which occur with advections of air masses of maritime origin. The largest number of CG discharges occurs under eastern flow and their hybrids with anticyclonic situations. Thunderstorms with greater CG lightning activity, highlighted by a higher concentration index, are located in areas with a higher density of lightning strikes, above all in mountainous areas away from the sea. The modeling of lightning density with geographic variables shows the positive influence of altitude and, particularly, distance to the sea, with nonlinear relationships due to the complex orography of the region. Likewise, areas with convex topography receive more lightning strikes than concave ones, a relation which has been demonstrated for the first time from a GAM. 相似文献
6.
Mohamed I. Ramadan Ebraheem H. Ramadan Marwan M. Khashila 《Geotechnical and Geological Engineering》2018,36(3):1545-1558
In urban areas, there are many situations where basement of new constructions or underground utilities are proposed to be constructed adjacent to old buildings. Of greatest concern are buildings with shallow foundations that do not extend below the zone of influence of the adjacent excavation. For deep excavation, the presence of a cantilever stage at the beginning of a construction sequence can often lead to excessive movements. Therefore over-excavation can also be a primary cause of excessive movements. In the present study, shallow excavation was considered. Three Dimensional Finite Element (3D FE) study was carried out in the present study. A cantilever contiguous pile wall was selected because it is common and relatively economic to be used in cohesive soil. Parametric study were performed considering excavation depth, pile embedded depth, and wall stiffness. Some design recommendations were given to provide a safe supporting system in clay. 相似文献
7.
《Geoforum》2014
Most studies on the causes of deforestation have sought to link the phenomenon to specific economic, political, or demographic factors, usually through statistical or spatial-statistical modeling. However, generalizations about the link between deforestation and specific variables or classes of variables are of questionable validity. Another approach, one that is receiving growing attention, seeks instead to identify particular contexts or situations, as created by an array of interacting factors, which encourage forms of land use or other economic activity that can generate deforestation pressure. Such an approach was used in this study to explore recent trends and dynamics in the Petén region of northern Guatemala. The research found a number of regional and national scale factors that in combination have led to a process of de-agrarianization and dispossession among smallholders, while large scale, commercial activities in agriculture, ranching and plantation forestry increasingly dominate. Rapid land concentration, in conjunction with limited employment generation through emergent activities, is intensifying pressure on remaining areas of forest. A focus on two distinct areas within Petén reveals how broader-scale trends and features can have differing outcomes at the local level, with contrasting socioeconomic and environmental effects. Finally, the paper explores the implications of recent dynamics in Petén for both policy and theory in relation to deforestation, agrarian change, and regional development. Key factors and questions are highlighted that should be considered when exploring influences on regional socioeconomic and environmental conditions. 相似文献
8.
A high-frequency echo-sounder (200 kHz) was used to characterize the sediments of the shallow Öre Estuary in the Gulf of Bothnia, northern Sweden. The acoustic signal patterns of the echogram were used to differentiate between fine-grained and coarse-grained sediment bottoms according to four major criteria: roughness of the line surface, line thickness, and occurrence of white line and double echo. The echogram characteristics were calibrated against physical properties of the sediment determined in the laboratory. It can be concluded that high-frequency echo-sounding offers an easily applied and reliable method for determining the spatial extent of different bottom sediments (e.g., fine-grained) in shallow waters. 相似文献
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An expert system is developed for evaluating failure potential of cut slopes and embankments. The fuzzy sets theory is used
with the modified Monte Carlo simulation technique to obtain the Slope Failure Potential Index (SFPI) incorporating factors
affecting slope stability, such as geology, topography, geomorphology, precipitation, vegetation and drainage conditions.
The developed Cut Slopes and Embankments Expert System (CSEES) includes a classification system for evaluating failure potential
of cut slopes and embankments, and a data bank on landslides in Jordan. The proposed classification system and slope failure-potential
method proved to be successful for the areas that experienced landslides in the past. The expert system can be used directly
for areas with the same geological formations as those areas in which landslides occurred in the past and can be used for
areas with other geological formations by modifying the rock type or foundation-material type factor incorporated in the expert
system.
Received: 18 February 1998 · Accepted: 19 October 1998 相似文献
11.
Abstract Karst areas have much higher ecological vulnerability and are easy to be contaminated by polychlorinated biphenyls(PCBs) which are introduced as health risk pollutants.PCBs concentrations were used to understand the transport behavior of PCBs conducted in the karst Nanshan Underground River,China.Water and sediments from the underground river water,and sediments and soil from the surface of the corresponding watershed were collected monthly in 2011 and 2012 and PCBs were analyzed.Seasonal variations were found in concentrations of PCBs both in the waters and sediments.PCBs concentrations varied from 0.3 to 29.9 ng·L-1 in the groundwater,while from 0.1 to 366.1 ng·g-1 in the underground sediments.Correlations were found in concentrations of PCBs in waters and sediments between the underground river and surface systems which indicate that the surface systems play a major role for the transport of PCBs and contamination in the underground river systems.Karst features are liable for the transport behavior.The underground river waters transport PCBs at mean 3 g·day-1. 相似文献
12.
François-Michel Le Tourneau 《GeoJournal》2018,83(4):803-817
More than half of the US rural population lives inside metro or micropolitan areas and even at more disaggregated scales, such as the census tracts, most spatial units mix rural and urban population. At a national scale, only 30% of the country are inhabited by 100% urban or 100% rural population, implying that more than two third of the US territory are somewhere in between both situations. As the rural/urban dichotomy appears today to be blurred by the emergence of new phenomena like rurbanization or exurbanization, our perception of rural America may be somewhat twisted and the reality of rural areas underplayed. This paper focuses on using finer-grade spatial units such as the census blocks and block groups, in order to provide new elements about the extension, localization and characteristics of rural America as well as about its inner dynamics. To that end, we analyze and process geographical and social data at these two levels of information, and use population density as a main factor of analysis. This allows us not only to propose new measurement of the extent of rural space in the USA but also to propose a new vision of its spatial dynamics by studying how several social indicators such as income, median age or sex ratio reveal regional and micro-regional variations and situations in the rural part of the US. 相似文献
13.
在新近杂填土上建厂，因杂填土松散、厚度大、基岩埋深大，若采用基岩作天然地基即用人工挖孔桩或机械成孔灌注桩，则很不经济，施工也存在安全隐患，易坍孔，且工期长。经过比较，采用灰土碎石挤密桩对杂填土进行处理后，作复合地基，施工易于操作并极大的缩短了工期，取得了良好的效果。 相似文献
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Sylvana Melo dos Santos Jaime Joaquim da Silva Pereira Cabral Ivaldo Dario da Silva Pontes Filho 《Natural Hazards》2012,64(1):421-439
The global positioning system (GPS) is widely used for determining the three-dimensional position of points on earth surface. In the last few years, its use has also been increasingly employed for obtaining vertical geometric coordinates, which associated with the orthometrical altitude of the point can be employed in various civil engineering applications, as has been seen in diverse localities throughout the world. The satisfactory performance of this technology for obtaining excellent precision in vertical coordinates demands some conditions, related to the satellites, such as transmission of signals and, principally, in the case of urbanized areas, the presence of obstructions in the proximity of the equipment, which interferes with the quality and quantity of the information collected. GPS is an efficient technique for the detection of small movements, including the monitoring of soil subsidence. The present article describes adequate forms of the use of GPS in such a way as to guarantee good precision of the resulting vertical coordinates, even under unfavorable situations, such as in coastal areas, where the reference networks for monitoring are implanted in only one of the sides of the point?Cobject region, which makes the situation more difficult and requires careful planning so that the use of GPS reaches the desired precision. 相似文献
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《International Geology Review》2012,54(7):909-919
There are seven principal aquifers in the Carboniferous rocks of the Moscow basin. These are replenished by 1) precipitation on the outcrops, 2) water-bearing horizons in the overlying Mesozoic and Quaternary, and 3) directly from lakes and rivers in favorable situations. Total exchange time (time for complete recharge) is estimated at 85 years, which is remarkably short for a basin of that size and capacity. Water from these aquifers has been used for almost 100 years. Cones of depression in the Upper and Middle Carboniferous are 65–90 km across, with lowering of 25–50 m of the water table; in the Lower Carboniferous, 150–180 km in diameter, with lowering up to 70 m. In areas of direct recharge from a stream the cone of depression is very small and shallow. The authors believe that because of the favorable recharge situation water yield of the basin can be greatly increased. -- E. Ingerson. 相似文献
20.
青木关岩溶槽谷地下水水源地固有脆弱性评价 总被引：2，自引：1，他引：1
岩溶地下水脆弱性评价是基于保护岩溶含水层从而有效地管理和利用地下水提出的有效方法和手段。我国西南岩溶区大多数地区缺少应有的地下水保护带,地下水比较容易受到污染。通过采用改进的斯洛文尼亚模式,考虑四个因子:覆盖层(O)、径流特征(C)、降雨条件(P)、岩溶发育程度(K),对重庆市青木关岩溶槽谷地下水水源地的固有脆弱性进行了定量评价。结果表明:流域范围内12.6%为高脆弱性地区;43%为中等脆弱性;44.4%为低脆弱性区域。消水洞及周边100m和消水河及其两边10m,以及岩溶管道发育地区为高脆弱性区。大部分岩溶区为中等脆弱性区。砂岩地区为低脆弱性地区。评价结果与实际吻合。该评价结果为各级决策部门合理规划利用和保护地下水资源提供简单明了的科学依据。该方法对于川东岩溶槽谷地区脆弱性评价有推广价值。 相似文献