排序方式： 共有17条查询结果，搜索用时 15 毫秒
1.
Ghorbanzadeh Omid Shahabi Hejar Crivellari Alessandro Homayouni Saeid Blaschke Thomas Ghamisi Pedram 《Landslides》2022,19(4):929-939
Landslides - Recent landslide detection studies have focused on pixel-based deep learning (DL) approaches. In contrast, intuitive annotation of landslides from satellite imagery is based on... 相似文献
2.
Potash in a salt mushroom at Hormoz Island, Hormoz Strait, Iran 总被引：2，自引：0，他引：2
Increasing volumes of potash are currently being discovered in a cluster of diapirs of Hormoz (formerly Hormuz) salt near Bandar Abbas, Iran. Most of the potash beds studied so far occur in complex recumbent folds in a salt mountain that would be difficult to exploit safely. However, Holocene marine erosion removed any salt mountains from a sub-group of near-shore Zagros diapirs and exposed their deeper structural levels. Even though these diapirs are still active, their potash deposits are likely more tractable to safe exploitation than in a salt mountain — as we make clear here for Hormoz Island.Geochemical surveys on Hormoz Island reveal two separate potash anomalies that are valuable pseudo-stratigraphic markers. Integrating field measurements of the attitudes of bedding with lineaments on air photos suggests that Hormoz Island consists of a mature bell- or plume-shaped mushroom diapir with potash beds wound around a toroidal axis of rotation near current exposure levels.2D numerical models simulate the salt mushroom on Hormoz Island and its internal circulation. They also suggest that the diapir has a wide overhand above a narrow stem in this gas-rich region. We use the mushroom diapir model to outline a regional exploration strategy that has the potential of influencing the world potash market thereafter. 相似文献
3.
Satarzadeh Eslam Sarraf Amirpouya Hajikandi Hooman Sadeghian Mohammad Sadegh 《Natural Hazards》2022,111(2):1355-1373
Natural Hazards - On March 25, 2019, widespread flood events occurred across Iran’s provinces and set a new record for socioeconomic losses and casualties. In hindsight, it opened an... 相似文献
4.
M.J. Valadan Zoej M. Mokhtarzade A. Mansourian H. Ebadi S. Sadeghian 《International Journal of Applied Earth Observation and Geoinformation》2007,9(4):403-413
In the absence of either satellite ephemeris information or camera model, rational functions are introduced by many investigators as mathematical model for image to ground coordinate system transformation. The dependency of this method on many ground control points (GCPs), numerical complexity, particularly terms selection, can be regarded as the most known disadvantages of rational functions. This paper presents a mathematical solution to overcome these problems. Genetic algorithms are used as an intelligent method for optimum rational function terms selection. The results from an experimental test carried out over a test field in Iran are presented as utilizing an IKONOS Geo image. Different numbers of GCPs are fed through a variety of genetic algorithms (GAs) with different control parameter settings. Some initial constraints are introduced to make the process stable and fast. The residual errors at independent check points proved that sub-pixel accuracies can be achieved even when only seven and five GCPs are used. GAs could select rational function terms in such a way that numerical problems are avoided without the need to normalize image and ground coordinates. 相似文献
5.
Syud Amer Ahmed Noah S. Diffenbaugh Thomas W. Hertel David B. Lobell Navin Ramankutty Ana R. Rios Pedram Rowhani 《Global Environmental Change》2011,21(1):46-55
Climate volatility could change in the future, with important implications for agricultural productivity. For Tanzania, where food production and prices are sensitive to climate, changes in climate volatility could have severe implications for poverty. This study uses climate model projections, statistical crop models, and general equilibrium economic simulations to determine how the vulnerability of Tanzania's population to impoverishment by climate variability could change between the late 20th Century and the early 21st Century. Under current climate volatility, there is potential for a range of possible poverty outcomes, although in the most extreme of circumstances, poverty could increase by as many as 650,000 people due to an extreme interannual decline in grain yield. However, scenarios of future climate from multiple climate models indicate no consensus on future changes in temperature or rainfall volatility, so that either an increase or decrease is plausible. Scenarios with the largest increases in climate volatility are projected to render Tanzanians increasingly vulnerable to poverty through impacts on staple grains production in agriculture, with as many as 90,000 additional people entering poverty on average. Under the scenario where precipitation volatility decreases, poverty vulnerability decreases, highlighting the possibility of climate changes that oppose the ensemble mean, leading to poverty impacts of opposite sign. The results suggest that evaluating potential changes in volatility and not just the mean climate state may be important for analyzing the poverty implications of climate change. 相似文献
6.
L. K. Harra V. Archontis E. Pedram A. W. Hood D. L. Shelton L. van Driel-Gesztelyi 《Solar physics》2012,278(1):47-71
In this paper we analyse the flux emergence that occurred in the following polarity area of an active region on 1 – 2 December
2006. Observations have revealed the existence of fast outflows at the edge of the emerging flux region. We have performed
3-D numerical simulations to study the mechanisms responsible for these flows. The results indicate that these outflows are
reconnection jets or pressure-driven outflows, depending on the relative orientation of the magnetic fields in contact (i.e. the emerging flux and the active region’s field which is favourable for reconnection on the west side and nearly parallel
with the pre-existing field on the east side of the emerging flux). In the observations, the flows are larger on the west
side until late in the flux emergence, when the reverse is true. The simulations show that the flows are faster on the west
side, but do not show the east flows increasing with time. There is an asymmetry in the expansion of the emerging flux region,
which is also seen in the observations. The west side of the emerging flux region expands faster into the corona than the
other side. In the simulations, efficient magnetic reconnection occurs on the west side, with new loops being created containing
strong downflows that are clearly seen in the observations. On the other side, the simulations show strong compression as
the dominant mechanism for the generation of flows. There is evidence of these flows in the observations, but the flows are
stronger than the simulations predict at the later stages. There could be additional small-angle reconnection that adds to
the flows from the compression, as well as reconnection occurring in larger loops that lie across the whole active region. 相似文献
7.
This study presents a numerical multi-scale simulation framework which is extended to accommodate hybrid simulation (numerical-experimental integration). The framework is enhanced with a standardized data exchange format and connected to a generalized controller interface program which facilitates communication with various types of laboratory equipment and testing configurations. A small-scale experimental program was conducted using a six degree-of-freedom hydraulic testing equipment to verify the proposed framework and provide additional data for small-scale testing of shearcritical reinforced concrete structures. The specimens were tested in a multi-axial hybrid simulation manner under a reversed cyclic loading condition simulating earthquake forces. The physical models were 1/3.23-scale representations of a beam and two columns. A mixed-type modelling technique was employed to analyze the remainder of the structures. The hybrid simulation results were compared against those obtained from a large-scale test and finite element analyses. The study found that if precautions are taken in preparing model materials and if the shear-related mechanisms are accurately considered in the numerical model, small-scale hybrid simulations can adequately simulate the behaviour of shear-critical structures. Although the findings of the study are promising, to draw general conclusions additional test data are required. 相似文献
8.
Studying the mechanical characteristics of weak sedimentary rocks is a burning issue in civil and mining engineering designs and analysis since obtaining rock mechanical properties of these has always faced lots of problems and uncertainties due to the structural weaknesses. One of the main causes of these problems is the difficulty of preparing high-quality core specimens recommended by testing standards or suggested methods for uniaxial compressive strength (UCS). For resolving this issue, in this study, common methods for indirect estimation of UCS of weak rocks were initially studied, their merits and demerits were analyzed, and then, in light of their positive and negative points, a new modified device was designed with a different mechanical structure and force exertion system, which could be practically used to present a new method for indirect estimation of UCS. Thus, in this study, we initially had a general view of the new dynamic needle penetrometer and its modified parts and their capabilities. After introduction, as the first phase of the practical studies on this, dynamic needle penetration resistance (DNPR) was measured, as the dynamic needle penetrometer test result, from 65 specimens collected from three different projects. Then, the relationships between DNPR and UCS of the rock specimens and the regressions of correlations were statistically analyzed. Finally, a linear equation with considerable accuracy resulted from analysis, and using this led to solving the main problem of this research by proposing a developed method for indirect estimation of uniaxial compressive strength of weak rocks. 相似文献
9.
Pedram Rowhani Olivier Degomme Debarati Guha-Sapir Eric F. Lambin 《Climatic change》2011,105(1-2):207-222
Changes in climate, along with anthropogenic pressures, impact vegetation productivity and related ecosystem services on which human security relies. The impacts of these climate changes on society will be experienced both through changes in mean conditions over long time periods and through increases in extreme events. Uncertainties remain on how short-term changes in ecosystems influence human security. Most studies analyzing the relationship between human security and climate are at the country level, ignoring fine-grained spatial heterogeneity in local climatic and socio-economic conditions. Here, we used detailed spatio-temporal information extracted from wide-swath satellite data (MODIS) to examine the impact of interannual variability in ecosystems on malnutrition and armed conflict in East Africa while controlling for other natural and socio-economic factors. The analysis was performed at a subnational and village scales. At the regional level, ecosystem variability was associated with malnutrition. This relationship was not statistically significant at the village level. At both levels of analysis, our results indicated that armed conflicts were more likely in regions with more vegetation. Results suggested that, in East Africa, increased levels of malnutrition were related to armed conflicts. They also showed the importance, in low-income countries, of local economic activity and accessibility to reduce the likelihood of malnutrition and insecurity. 相似文献
10.
Drought Forecasting in a Semi-arid Watershed Using Climate Signals:a Neuro-fuzzy Modeling Approach 总被引：6，自引：3，他引：3
Bahram CHOUBIN Shahram KHALIGHI-SIGAROODI Arash MALEKIAN Sajjad AHMAD Pedram ATTAROD 《山地科学学报》2014,(6):1593-1605
Large-scale annual climate indices were used to forecast annual drought conditions in the Maharlu-Bakhtegan watershed,located in Iran,using a neuro-fuzzy model.The Standardized Precipitation Index（SPI） was used as a proxy for drought conditions.Among the 45 climate indices considered,eight identified as most relevant were the Atlantic Multidecadal Oscillation（AMO）,Atlantic Meridional Mode（AMM）,the Bivariate ENSO Time series（BEST）,the East Central Tropical Pacific Surface Temperature（NINO 3.4）,the Central Tropical Pacific Surface Temperature（NINO 4）,the North Tropical Atlantic Index（NTA）,the Southern Oscillation Index（SOI）,and the Tropical Northern Atlantic Index（TNA）.These indices accounted for 81% of the variance in the Principal Components Analysis（PCA） method.The Atlantic surface temperature（SST：Atlantic） had an inverse relationship with SPI,and the AMM index had the highest correlation.Drought forecasts of neuro-fuzzy model demonstrate better prediction at a two-year lag compared to a stepwise regression model. 相似文献