Simulation of urban expansion via integrating artificial neural network with Markov chain – cellular automata     

Tingting Xu  Jay Gao  Giovanni Coco 《International journal of geographical information science》2019,33(10):1960-1983

Accurate simulations and predictions of urban expansion are critical to manage urbanization and explicitly address the spatiotemporal trends and distributions of urban expansion. Cellular Automata integrated Markov Chain (CA-MC) is one of the most frequently used models for this purpose. However, the urban suitability index (USI) map produced from the conventional CA-MC is either affected by human bias or cannot accurately reflect the possible nonlinear relations between driving factors and urban expansion. To overcome these limitations, a machine learning model (Artificial Neural Network, ANN) was integrated with CA-MC instead of the commonly used Analytical Hierarchy Process (AHP) and Logistic Regression (LR) CA-MC models. The ANN was optimized to create the USI map and then integrated with CA-MC to spatially allocate urban expansion cells. The validated results of kappa and fuzzy kappa simulation indicate that ANN-CA-MC outperformed other variously coupled CA-MC modelling approaches. Based on the ANN-CA-MC model, the urban area in South Auckland is predicted to expand to 1340.55 ha in 2026 at the expense of non-urban areas, mostly grassland and open-bare land. Most of the future expansion will take place within the planned new urban growth zone.  相似文献   

Strict positive definiteness under axial symmetry on the sphere     

Bissiri  Pier Giovanni  Peron  Ana Paula  Porcu  Emilio 《Stochastic Environmental Research and Risk Assessment (SERRA)》2020,34(5):723-732

Stochastic Environmental Research and Risk Assessment - Axial symmetry for covariance functions defined over spheres has been a very popular assumption for climate, atmospheric, and environmental...  相似文献   

Julius Obsequens’s book,Liber Prodigiorum: A Roman era record of meteorite falls,fireballs, and other celestial phenomena     

Annarita Franza  Giovanni Pratesi 《Meteoritics & planetary science》2020,55(7):1697-1708

Julius Obsequens was the pseudonym of a Roman historian presumably living in the 4th century ad , whose life is shrouded in mystery. All that is known about Obsequens’s biography is that he was the author of a book entitled Liber Prodigiorum (Book of Prodigies), a collection of prodigies deduced from Livy’s Ab Urbe Condita Libri (Books from the Founding of the City). The Liber Prodigiorum covered the period from 190 to 11 bc and gathered a chronological list of portents of various kinds (e.g., births of monstrous animals or men, statues that shed blood, voices from beyond the grave, epidemics, earthquakes, unidentified flying objects). Among these extraordinary reports, chronicles of celestial phenomena were also included. The interdisciplinary approach adopted in this research has clarified the nature of the events described in the text and has enabled the identification of new Italian meteorite falls that are not included in the Meteoritical Bulletin Database.  相似文献   

Experiments on Surface Waves Interacting with Flexible Aquatic Vegetation     

Luca Cavallaro  Antonino Viviano  Giovanni Paratore  Enrico Foti 《Ocean Science Journal》2018,53(3):461-474

Surface wave interaction with aquatic vegetation appears to play a key role in coastal hydro-morpho-dynamics. As an example, the presence of a dense meadow at intermediate water depth is usually associated with a stable and resilient shore. Wave-meadow interactions are investigated here by means of physical modelling, with a focus on wave height distribution and hydrodynamics. The central part of a wave flume is covered by flexible artificial seagrass, composed of polyethylene leaves. This vegetation is tested in both near emergent and submerged conditions. The wave height reduction is evaluated by means of a drag coefficient defined from linear wave theory, which contains all the unknowns of the adopted methodology. The behaviour of such a coefficient is investigated as a function of a wave related Reynolds number. The influence of the flexibility of the leaves is also considered, together with a wave frequency parameter. The results show a complex behaviour with three different trends for near rigid, intermediate or highly flexible leaves. Amplitudes of the orbital velocities are investigated and show a fairly good match with the linear wave theory. On the contrary, the mean velocity along the water column appears to be modified by the seagrass for submerged leaves.  相似文献   

Natural highways for end-of-life solutions in the LEO region     

Elisa Maria Alessi  Giulia Schettino  Alessandro Rossi  Giovanni B. Valsecchi 《Celestial Mechanics and Dynamical Astronomy》2018,130(5):34

We present the main findings of a dynamical mapping performed in the Low Earth Orbit region. The results were obtained by propagating an extended grid of initial conditions, considering two different epochs and area-to-mass ratios, by means of a singly averaged numerical propagator. It turns out that dynamical resonances associated with high-degree geopotential harmonics, lunisolar perturbations and Solar radiation pressure can open natural deorbiting highways. For area-to-mass ratios typical of the orbiting intact objects, these corridors can be exploited only in combination with the action exerted by the atmospheric drag. For satellites equipped with an area augmentation device, we show the boundary of application of the drag, and where the Solar radiation pressure can be exploited.  相似文献   

Sand particle velocities over a subaqueous dune slope using high-frequency image capturing     

Renske C. Terwisscha van Scheltinga  Giovanni Coco  Heide Friedrich 《地球表面变化过程与地形》2019,44(10):1881-1894

This work presents measurements and analysis of sand particle velocities over a subaqueous dune with median sand diameter of 0.85 mm. Time-lapse images of the mobile bed and an automated particle image velocimetry (PIV)-based cross-correlation method are used to obtain mean velocity of sand particles. This technique is shown to be consistent with measurements obtained with manual tracing. The measurements indicate an increase in mean particle velocity over a dune slope. Three regions are distinguished over the dune slope: (1) region of fluctuating particle velocity, (2) region of increasing particle velocity, and (3) region of maximum particle velocity. The observations are aligned with experimental and numerical modelling studies, indicating fluctuations in flow velocity over a dune stoss slope. We furthermore show that the standard deviation of the mean particle velocity is affected by the slope location and decreases from the lower slope towards the upper slope. The particle velocity variability is discussed in the context of general onset and cessation of sediment transport, the effect of the reattachment zone, sweep-transport events, and the existence of superimposed bedforms. With this work we bridge the gap between measurements of bedload transport at the particle-scale and at the bedform-scale. © 2019 John Wiley & Sons, Ltd.  相似文献   

Rockfall seismic features analysis based on in situ tests:frequency,amplitude, and duration     

Liang FENG  Veronica PAZZI  Emanuele INTRIERI  Teresa GRACCHI  Giovanni GIGLI 《山地科学学报》2019,(5)

In the seismic event classification,determining the seismic features of rockfall is significantly important for the automatic classification of seismic events because of the huge amount of raw data recorded by seismic stations in continuous monitoring. At the same time, the rockfall seismic features are still not completely understood.This study concentrates on the rockfall frequency content, amplitude(ground velocity), seismic waveform and duration analysis, of an artificial rockfall test at Torgiovannetto(a former quarry in Central Italy). A total of 90 blocks were released in the test, and their seismic signals and moving trajectories were recorded by four tri-axial seismic stations and four cameras, respectively. In the analysis processing,all the artificial rockfall signal traces were cut separately and the seismic features were extracted individually and automatically. In this study, the relationships between a) frequency content and impacted materials, b) frequency content and the distance between block releasing position and seismic station(source-receiver distance) were discussed. As a result, we found that the frequency content of rockfall focuses on 10-60 Hz and 80-90 Hz within a source-receiver distance of 200 m, and it is well correlated with impacted material and source-receiver distance. To evaluate the difference between earthquake and rockfall, 23 clear earthquake signals recorded in a seven month-long continuous seismic monitoring, carried out with the four seismic stations, were picked out, according to the Italian national earthquakes database(INGV). On these traces we performed the same analysis as in the artificial rockfall traces, and two parameters were defined to separate rockfall events from earthquake noise. The first one, the amplitude ratio, is related to the amplitude variation of rockfall between two stations and is greater than that of earthquakes, because of the higher attenuation occurring for rockfall events, which consists in high frequencies whereas for earthquakes it consists in low frequencies. The other parameter, the shape of waveform of signal trace, showed a significant difference between rockfall and earthquake and that could be a complementary feature to discriminate between both. This analysis of artificial rockfall is a first step helpful to understand the seismic characteristics of rockfall, and useful for rockfall seismic events classification in seismic monitoring of slope.  相似文献   

Soil water dynamics under different forest vegetation cover: Implications for hillslope stability   总被引：1，自引：0，他引：1       下载免费PDF全文

Elyas Hayati  Ehsan Abdi  Mohsen Mohseni Saravi  John L. Nieber  Baris Majnounian  Giovanni B. Chirico  Bruce Wilson  Moharramali Nazarirad 《地球表面变化过程与地形》2018,43(10):2106-2120

Though it is well known that vegetation affects the water balance of soils through canopy interception and evapotranspiration, its hydrological contribution to soil hydrology and stability is yet to be fully quantified. To improve understanding of this hydrological process, soil water dynamics have been monitored at three adjacent hillslopes with different vegetation covers (deciduous tree cover, coniferous tree cover, and grass cover), for nine months from December 2014 to September 2015. The monitored soil moisture values were translated into soil matric suction (SMS) values to facilitate the analysis of hillslope stability. Our observations showed significant seasonal variations in SMS for each vegetation cover condition. However, a significant difference between different vegetation covers was only evident during the winter season where the mean SMS under coniferous tree cover (83.6 kPa) was significantly greater than that under grass cover (41 kPa). The hydrological reinforcing contribution due to matric suction was highest for the hillslope with coniferous tree cover, while the hillslope with deciduous tree cover was second and the hillslope with grass cover was third. The greatest contributions for all cover types were during the summer season. During the winter season, the wettest period of the monitoring study, the additional hydrological reinforcing contributions provided by the deciduous tree cover (1.5 to 6.5 kPa) or the grass cover (0.9 to 5.4 kPa) were insufficient to avoid potential slope failure conditions. However, the additional hydrological reinforcing contribution from the coniferous tree cover (5.8 to 10.4 kPa) was sufficient to provide potentially stable hillslope conditions during the winter season. Our study clearly suggests that during the winter season the hydrological effects from both deciduous tree and grass covers are insufficient to promote slope stability, while the hydrological reinforcing effects from the coniferous tree cover are sufficient even during the winter season. Copyright © 2018 John Wiley & Sons, Ltd.  相似文献   

How deep can forest vegetation cover extend their hydrological reinforcing contribution?          下载免费PDF全文

Elyas Hayati  Ehsan Abdi  Mohsen Mohseni Saravi  John L. Nieber  Baris Majnounian  Giovanni B. Chirico 《水文研究》2018,32(16):2570-2583

An experimental campaign was set up to quantify the contribution of evapotranspiration fluxes on hillslope hydrology and stability for different forest vegetation cover types. Three adjacent hillslopes, respectively, covered by hardwood, softwood, and grass were instrumented with nine access tubes each to monitor soil water dynamics at the three depths of 30, 60, and 100 cm, using a PR2/6 profile probe (Delta‐T Devices Ltd) for about 6 months including wet periods. Soil was drier under softwood and wetter under grass at all the three depths during most of the monitoring period. Matric suction derived via the soil moisture measurements was more responsive to changes in the atmospheric conditions and also recovered faster at the 30 cm depth. Results showed no significant differences between mean matric suction under hardwood (101.6 kPa) with that under either softwood or grass cover. However, a significant difference was found between mean matric suction under softwood (137.5 kPa) and grass (84.3 kPa). Results revealed that, during the wettest period, the hydrological effects from all three vegetation covers were substantial at the 30 cm depth, whereas the contribution from grass cover at 60 cm (2.0 kPa) and 100 cm (1.1 kPa) depths and from hardwood trees at 100 cm depth (1.2 kPa) was negligible. It is surmised that potential instability would have occurred at these larger depths along hillslopes where shallow hillslope failures are most likely to occur in the region. The hydrological effects from softwood trees, 8.1 and 3.9 kPa, were significant as the corresponding factor of safety values showed stable conditions at both depths of 60 and 100 cm, respectively. Therefore, the considerable hydrological reinforcing effects from softwood trees to the 100 cm depth suggest that a hillslope stability analysis would show that hillslopes with softwood trees will be stable even during the wet season.  相似文献   

Archaeoseismological evidence of past earthquakes in Rome (fifth to ninth century A.D.) used to quantify dating uncertainties and coseismic damage     

Fabrizio Galadini  Giovanni Ricci  Emanuela Falcucci  Camilla Panzieri 《Natural Hazards》2018,94(1):319-348

The transformation of Rome during the Late Antiquity and the Early Middle Ages has been investigated by archaeologists and historians. Social and political changes are the main aspects which led to a progressive modification of the urban framework; abandonment, spoliation and transformation of buildings are quite diffused as documented by the archaeological literature. The consequence of these practices is a higher vulnerability of the buildings which, from the seismological point of view, played a main role in increasing the effects of seismic shaking. A number of earthquakes have struck Rome during the period of investigation (fifth to ninth century A.D.), known from historical sources: 443, 484–508, 618, 801, 847; in some cases (443, 484–508, 801) damage has been documented. In contrast, the archaeological sources characterise collapse layers and evidence of destruction at different sites with changing and not always conclusive chronological constraints. Consequently, collapse and destruction have been alternatively attributed to the above-mentioned earthquakes. Through a geoarchaeological and stratigraphic analysis of potentially coseismic collapse units, we want (1) to describe the archaeoseismic evidence derived from recent excavations and from the available literature (e.g. Piazza Madonna di Loreto, Piazza Venezia, Palazzo Valentini Crypta Balbi, Colosseo, Basilica Hilariana, Basilica di Santa Petronilla, Santa Maria Antiqua,…); (2) to discuss the chronological problems and the uncertainty of attribution of the collapse units to known historical earthquakes; (3) to discuss the earthquake damage exaggeration due to erroneous attribution of seismic origin to the evidence of destruction derived from archaeological data. Finally, we will infer the role that earthquakes may have had on the development of the urban landscape in the fifth to ninth century A.D.  相似文献