Triplets of quasars at high redshift – I. Photometric data     

M. Victoria Alonso  Georgina V. Coldwell  Ilona Söchting  Carlos Bornancini  Malcolm G. Smith  Diego García Lambas  Armin Rest 《Monthly notices of the Royal Astronomical Society》2008,385(4):2254-2260

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Climate change adaptation: a systematic review on domains and indicators     

Salehi  Shiva  Ardalan  Ali  Garmaroudi  Gholamreza  Ostadtaghizadeh  Abbas  Rahimiforoushani  Abbas  Zareiyan  Armin 《Natural Hazards》2019,96(1):521-550

In recent years, climate change has been one of the most complicated problems that human being has faced. Climate change adaptation (CCA) is considered to be an important component of risk management. In order to achieve adaptation, it is necessary to determine the indicators influencing adaptation in each community and this requires measurement and standard tools. The aim of this study is to determine and categorize the indicators of CCA. International electronic databases including Science Direct, Web of Science, Scopus, Google Scholar were investigated for only articles published in English language. In addition, Iranian databases including Irandoc, SID, and Magiran were investigated. There was no limitation on the methods of studies. Furthermore, snowball method was used for finding more articles while the ProQuest database was searched for related dissertations. The published documents from 1990 to November 2017 were gathered in this study. Out of 4439 publications initially search, 152 full texts were investigated. Finally, a total of 45 potentially relevant citations were included for full text review; in addition, fourteen other sources were investigated. Using snowball method, we found 24 other articles that were included in our final result. From the searches, 176 indicators were identified, while seven main domains were mentioned. Since in the articles, domains of adaptation are not in the form of a model, it is better to focus on this issue in the future and it seems that prioritizing and weighting domains in adaptation in different communities with different needs are an important issue.

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Climate change and modelling of extreme temperatures in Switzerland   总被引：3，自引：3，他引：0  

Boriss Siliverstovs  Rainald Ötsch  Claudia Kemfert  Carlo C. Jaeger  Armin Haas  Hans Kremers 《Stochastic Environmental Research and Risk Assessment (SERRA)》2010,24(2):311-326

This study models maximum temperatures in Switzerland monitored in twelve locations using the generalised extreme value (GEV) distribution. The parameters of the GEV distribution are determined within a Bayesian framework. We find that the parameters of the underlying distribution underwent a substantial change in the beginning of the 1980s. This change is characterised by an increase both in the level and the variability. We assess the likelihood of the heat wave of the summer 2003 using the fitted GEV distribution by accounting for the presence of a structural break. The estimation results do suggest that the heat wave of 2003 is not that statistically improbable if an appropriate methodology is used for dealing with nonstationarity.  相似文献   

An improved fast level set method initialized with a combination of k-means clustering and Otsu thresholding for unsupervised change detection from SAR images     

Armin Moghimi  Safa Khazai  Ali Mohammadzadeh 《Arabian Journal of Geosciences》2017,10(13):293

Detection of changes in synthetic aperture radar (SAR) images is an important challenge due to the effects of speckle noise on these images. In recent years, appropriate methods for SAR-based-change detection have been developed based on the level set methods (LSM). These methods need to set parameters for defining a proper initial contour. Moreover, the gradient information is only employed in the total energy of these methods for segmentation of the difference image. In this study, a novel method has been proposed for unsupervised change detection of multitemporal SAR images based on the improved fast level set method (IFLSM) initialized with a combination of k-means and Otsu techniques. The proposed method utilizes the discrete wavelet transform (DWT) fusion strategy and edge enhancement to achieve a noise-resistant difference image from the mean-ratio and log-ratio images. Afterward, the generated binary change map (CM) by applying a combination of k-means and Otsu techniques on the difference image is used as the initial contour to achieve a final CM on difference image using the IFLSM. To check advantages of the proposed method, experiments are applied on two sets of multitemporal SAR images corresponding to artificial Chitgar Lake (under reconstruction) in Tehran (Iran) taken by TerraSAR-X satellite in 2011 and 2012, and corresponding to San Pablo and Briones reservoirs in California (USA) acquired by ERS-2 satellite in 2003 and 2004. Results of proposed method were compared with results of some well-known unsupervised change detection methods. Experimental results prove the sufficiency of the proposed method in unsupervised change detection in terms of accuracy, implementation time, and computational complexity.  相似文献   

A history of violence: magma incubation,timing and tephra distribution of the Los Chocoyos supereruption (Atitlán Caldera,Guatemala)     

Alejandro Cisneros de León  Julie C. Schindlbeck-Belo  Steffen Kutterolf  Martin Danišík  Axel K. Schmitt  Armin Freundt  Wendy Pérez  Janet C. Harvey  Kuo-Lung Wang  Hao-Yang Lee 《第四纪科学杂志》2021,36(2):169-179

The climactic Los Chocoyos (LCY) eruption from Atitlán caldera (Guatemala) is a key chronostratigraphic marker for the Quaternary period given the extensive distribution of its deposits that reached both the Pacific and Atlantic Oceans. Despite LCY tephra being an important marker horizon, a radioisotopic age for this eruption has remained elusive. Using zircon (U–Th)/He geochronology, we present the first radioisotopically determined eruption age for the LCY of 75 ± 2 ka. Additionally, the youngest zircon crystallization ²³⁸U–²³⁰Th rim ages in their respective samples constrain eruption age maxima for two other tephra units that erupted from Atitlán caldera, W-Fall (130 ⁺¹⁶/₋₁₄ ka) and I-Fall eruptions (56 ^+8.2/_−7.7 ka), which under- and overlie LCY tephra, respectively. Moreover, rim and interior zircon dating and glass chemistry suggest that before eruption silicic magma was stored for >80 kyr, with magma accumulation peaking within ca. 35 kyr before the LCY eruption during which the system may have developed into a vertically zoned magma chamber. Based on an updated distribution of LCY pyroclastic deposits, a new conservatively estimated volume of ~1220 ± 150 km³ is obtained (volcanic explosivity index VEI > 8), which confirms the LCY eruption as the first-ever recognized supereruption in Central America.  相似文献   

Kinetic biomineralization through microfluidic chip tests     

Xiao  Yang  He  Xiang  Wu  Wei  Stuedlein  Armin W.  Evans  T. Matthew  Chu  Jian  Liu  Hanlong  van Paassen  Leon A.  Wu  Huanran 《Acta Geotechnica》2021,16(10):3229-3237

A homogeneous microfluidic chip was used to investigate the pore-scale characteristics during the process of microbially induced calcium carbonate precipitation (MICP). An image-processing scheme was developed to measure the projecting areas of the precipitated calcium carbonate. Calcium carbonate first precipitated on the bacterium side before spreading to the rest of the chip. The distribution of calcium carbonate was more uniform along the length of the microchip than along the width. Raman back-scattering spectroscopy was used to examine the chemical composition of the precipitate, identifying calcite and vaterite as the main mineral phases. Bacterium traces were noted on crystal surfaces in SEM images, suggesting a higher adsorptive capacity for irregular precipitates than well-shaped crystals.

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Assessment of key transport parameters in a karst system under different dynamic conditions based on tracer experiments: the Jeita karst system,Lebanon     

Joanna Doummar  Armin Margane  Tobias Geyer  Martin Sauter 《Hydrogeology Journal》2018,26(7):2283-2295

Artificial tracer experiments were conducted in the mature karst system of Jeita (Lebanon) under various flow conditions using surface and subsurface tracer injection points, to determine the variation of transport parameters (attenuation of peak concentration, velocity, transit times, dispersivity, and proportion of immobile and mobile regions) along fast and slow flow pathways. Tracer breakthrough curves (TBCs) observed at the karst spring were interpreted using a two-region nonequilibrium approach (2RNEM) to account for the skewness in the TBCs’ long tailings. The conduit test results revealed a discharge threshold in the system dynamics, beyond which the transport parameters vary significantly. The polynomial relationship between transport velocity and discharge can be related to the variation of the conduit’s cross-sectional area. Longitudinal dispersivity in the conduit system is not a constant value (α?=?7–10 m) and decreases linearly with increasing flow rate because of dilution effects. Additionally, the proportion of immobile regions (arising from conduit irregularities) increases with decreasing water level in the conduit system. From tracer tests with injection at the surface, longitudinal dispersivity values are found to be large (8–27 m). The tailing observed in some TBCs is generated in the unsaturated zone before the tracer actually arrives at the major subsurface conduit draining the system. This work allows the estimation and prediction of the key transport parameters in karst aquifers. It shows that these parameters vary with time and flow dynamics, and they reflect the geometry of the flow pathway and the origin of infiltrating (potentially contaminated) recharge.  相似文献   

Economic,institutional and technological uncertainties of emissions trading—a system dynamics modeling approach     

Irina Dolgopolova  Bo Hu  Armin Leopold  Stefan Pickl 《Climatic change》2014,124(3):663-676

System dynamics models are employed for analyzing the impact of different uncertainties on carbon emission trading–both on national and business levels. Economic, institutional and technological uncertainties significantly influence any country's benefits from emission permit trading. If a country participates in trading on the international market then the possible price range becomes the source of additional uncertainty. In the case of business investment decisions for implementing resource‐saving technology, our system dynamics model shows that the first‐mover investor will get significantly fewer advantages than his followers, which leads to delay in primary investment to the sector.  相似文献   

Everything moves:The rapid changes in photogrammetry and remote sensing     

Armin Gruen 《地球空间信息科学学报》2021,24(1):33-49

Changes in technology are coming at an ever increasing pace.This holds for photogrammetry and remote sensing as well."Everything moves"-this is why I chose this topic to shed some light on some of the recent developments.Naturally,this undertaking can never be complete in the sense of covering all developments in Photogrammetry and Remote Sensing.Besides,the impact of Deep Learning in photogrammetry is not mentioned in this paper.This is a very personal account.People may not agree with some of my findings,but this is in the nature of science.In any case,this contribution is meant as a tribute to Gottfried's successful lifelong work.It is not a scientific paper in the traditional sense but rather a collection of thoughts that emerged over the 50 years of my professional career.It is also meant for an audience who has not necessarily a deep photogrammetric expert know-how.  相似文献   

Testing the Quality of Sea-Level Data Using the GECCO Adjoint Assimilation Approach     

Martin G. Scharffenberg  Armin Köhl  Detlef Stammer 《Surveys in Geophysics》2017,38(1):349-383

Besides providing an estimate of the changing ocean state, an important result of the dynamically consistent estimating the circulation and climate of the ocean (ECCO) state estimate approach is the provision of a posterior model–data residuals which contain important information about elements in the assimilated observations that are inconsistent with the model dynamics or with the information present in other ocean data sets that are being used as constraints in the assimilation procedure. Based on decreased GECCO2 model–data residuals, upon using the altimeter data through the ESA climate change initiative (cci) sea-level (SL) project, we show here that the recently reprocessed ESA SL_cci altimeter data set (SL1) has been improved relative to the earlier AVISO altimetry data set and is now more consistent with the GECCO2 estimate and with the information about the changing ocean state embedded in other ocean data sets. The improvement can be shown to exist separately for both TOPEX/POSEIDON and ERS data sets. The study reveals that especially in regions characterized by small sea surface height (SSH) variability and small signal-to-noise ratio in the SSH data, improvements can be on the order of 30% of previously existing model–data residuals. However, in some regions we can find degradations, particulary in those where GECCO2 has little skill in representing the altimeter data and where evaluation of the products with GECCO2 is thus not advisable. Upon the assimilation of the new SL1 data set, the GECCO2 synthesis was further improved. However, adding the sea surface temperature (SST) from the SST_cci project as additional constrain, no further impact can be identified.  相似文献