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1.
Aurelian Andrei Radu Tatiana Angelescu Valentin Curtef Florin Delia Daniel Felea Ioana Goia Dumitru Ha?egan Bogdan Lucaschi Ancuta Manea Vlad Popa Ioan Rali?? Radu V?c?reanu 《Experimental Astronomy》2012,34(1):31-42
Around the world, several scientific projects share the interest of a global network of small Cherenkov telescopes for monitoring observations of the brightest blazars??the DWARF network. A small, ground based, imaging atmospheric Cherenkov telescope of last generation is intended to be installed and operated in Romania as a component of the DWARF network. To prepare the construction of the observatory, two support projects have been initiated. Within the framework of these projects, we have assessed a number of possible sites where to settle the observatory. In this paper we submit a brief report on the general characteristics of the best four sites selected after the local infrastructure, the nearby facilities and the social impact criteria have been applied. 相似文献
2.
Mihaela Constantin Aurelian C. Trandafir Marta C. Jurchescu Daniel Ciupitu 《Environmental Earth Sciences》2010,59(7):1569-1578
The May–August 2005 heavy rainstorm events in Romania triggered a large number of geomorphic hazards of great magnitude, consisting
of primarily floods and landslides. Some of the most affected regions were the Curvature Carpathians and Subcarpathians. This
paper addresses the effects of rainfall on slopes, especially in the middle sector of the Sibiciu basin (the Buzău Carpathians)
outlining the significant landslide damage along the road connecting the Colţi and Aluniş villages. The landslides are analyzed
in terms of geologic, geomorphic and engineering geologic features, focusing on the Colţi–Aluniş landslide which had the greatest
impact on the road displacement. The related environmental and social impacts are also discussed. 相似文献
3.
On October 27, 2004, a moderate size earthquake occurred in the Vrancea seismogenic region (Romania). The Vrancea seismic zone is an area of concentrated seismicity at intermediate depths beneath the bending area of the southeastern Carpathians. The 2004 M w?=?6 Vrancea subcrustal earthquake is the largest seismic event recorded in Romania since the 1990 earthquakes. With a maximum macroseismic intensity of VII Medvedev–Sponheuer–Kárník (MSK-64) scale, the seismic event was felt to a distance of 600 km from the epicentre. This earthquake caused no serious damage and human injuries. The main purpose of this paper is to present the macroseismic map of the earthquake based on the MSK-64 intensity scale. After the evaluation of the macroseismic effects of this earthquake, an intensity dataset has been obtained for 475 sites in the Romanian territory. Also, the maximum horizontal accelerations recorded in the area by the K2 network are compared to the intensity values. 相似文献
4.
Aurelian Catalin Trandafir Kyoji Sassa 《Geotechnical and Geological Engineering》2006,24(6):1627-1639
This paper outlines a methodology for evaluating the likelihood of catastrophic landslide occurrence on gentle slopes in liquefiable
soils during earthquake. The approach is based on a modified Newmark sliding block model of assessing the earthquake-induced
undrained landslide displacements for conditions of no shear stress reversals on the sliding surface. By employing the shear
resistance-displacement relationship from undrained monotonic ring shear tests, the simulation model incorporates the sensitivity
of computed displacements to variations in yield acceleration. The proposed approach involves an examination of undrained
seismic slope performance under various horizontal seismic waveforms scaled to different specific values of the peak earthquake
acceleration. An example problem illustrates how the proposed methodology may be used to demarcate, based on the magnitude
of permanent seismic displacement, the levels of low, moderate and high risk of catastrophic landslide on a gentle slope in
a saturated cohesionless soil susceptible to liquefaction during earthquake. 相似文献
5.
Aurelian Catalin Trandafir Toshitaka Kamai Roy Carl Sidle Mihail Popescu 《Geotechnical and Geological Engineering》2007,25(6):679-691
Failure of several gravity retaining walls in residential areas built on reclaimed land, during the October 23, 2004 Chuetsu
earthquake in Niigata Prefecture, Japan, determined the authorities to consider the seismic retrofit of the walls in order
to mitigate future similar disasters in the urban environment. This study addresses the effectiveness of ground anchors in
improving the seismic performance of such retaining structures through a sliding block analysis of the seismic response of
an anchored gravity retaining wall supporting a dry homogeneous fill slope subject to horizontal ground shaking. Sliding failure
along the base of the wall and translational failure along a planar slip surface of the active wedge within the fill material
behind the wall were considered in the formulation, whereas the anchor load was taken as a line load acting on the face of
the gravity retaining wall. The effects of magnitude and orientation of anchor load on the yield acceleration of the wall-backfill
system and seismically induced wall displacements were examined. It was found that for the same anchor orientation, the yield
acceleration increases in a quasi-linear manner with increasing the anchor load, whereas an anchor load of a given magnitude
acting at various orientations produces essentially identical yield accelerations. On the other hand, the computed earthquake-induced
permanent displacements of the anchored gravity retaining wall decrease exponentially with increasing magnitude of anchor
load. Additionally, the influence of backfill strength properties (e.g., internal friction angle) on the seismic wall displacement
appears to diminish considerably for the anchored gravity retaining wall. A dynamic displacement analysis conducted for the
anchored gravity retaining wall subjected to various seismic waveforms scaled to the same peak earthquake acceleration revealed
a good correlation between the calculated permanent wall displacements and the Arias intensity parameter characterizing the
input accelerogram. 相似文献
6.
This study demonstrates the utilization of a multi-objective hybrid global/local optimization algorithm for solving managed aquifer recharge (MAR) design problems, in which the decision variables included spatial arrangement of water injection and abstraction wells and time-variant rates of pumping and injection. The objective of the optimization was to maximize the efficiency of the MAR scheme, which includes both quantitative and qualitative aspects. The case study used to demonstrate the capabilities of the proposed approach is based on a published report on designing a real MAR site with defined aquifer properties, chemical groundwater characteristics as well as quality and volumes of injected water. The demonstration problems include steady state and transient scenarios. The steady state scenario demonstrates optimization of spatial arrangement of multiple injection and recovery wells, whereas the transient scenario was developed with the purpose of finding optimal regimes of water injection and recovery at a single location. Both problems were defined as multi-objective problems. The scenarios were simulated by applying coupled numerical groundwater flow and solute transport models: MODFLOW-2005 and MT3D-USGS. The applied optimization method was a combination of global (the non-dominated sorting genetic algorithm [NSGA-2]) and local (the Nelder-Mead downhill simplex search algorithms). The analysis of the resulting Pareto optimal solutions led to the discovery of valuable patterns and dependencies between the decision variables, model properties, and problem objectives. Additionally, the performance of the traditional global and the hybrid optimization schemes were compared. 相似文献
7.
Adina-Eliza Croitoru Iulian-Horia Holobaca Catalin Lazar Florin Moldovan Alexandru Imbroane 《Climatic change》2012,111(2):393-410
Air temperature variability and trends in Romania were analysed using monthly, seasonal, and annual datasets. Temperature
data of winter wheat season were also analysed. The Mann-Kendall test, Sen’s slope estimate, the sequential version of the
Mann-Kendall test, the Pettitt test and spatial and temporal hierarchical cluster analyses were used. First, the datasets
were checked for changing points. The 106-year period was divided into two long periods of 100 years each to verify the importance
of a very short interval in changing of general trends; after that it was divided into three shorter periods of 35–36 years
each. The main conclusions are as follows: the 6 years making up the difference between the two long periods are very important
in the context of the recent global warming; the three shorter periods analysis indicate some fluctuations rather than continuous
warming. The latest short period is the most relevant for global warming. Spatial hierarchical cluster analysis indicated
the existence of two distinctive groups. One of them, which includes stations in the south-east part of the country, seems
to be influenced by the Black Sea surface temperature. Temporal hierarchical cluster analysis reveals that annual data series
have the closest relation with the summer data series. Further, the impact of temperature changes on winter wheat phenology
was determined using a phenology simulation performed with the model from the Decision Support System for Agrotechnology Transfer
v. 4.0.2.0 platform. Earlier occurrences of anthesis and maturity were noticed for several regions in the country. 相似文献
8.
Over the past decade, land development activities on hillsides in northern Utah have resulted in a significant increase in
landslide activity throughout the region. The majority of recent landslides are shallow and they occurred on cut gentle slopes
especially during spring and early summer due to snowmelt induced elevated groundwater tables. The geologic material documented
at numerous landslide sites is a soft gray-green completely decomposed Norwood Tuff. The present study addresses the mechanism
of a shallow landslide in completely decomposed Norwood Tuff based on field, laboratory and numerical investigations. Detailed
slope surface geometry obtained from laser-scan surveys together with strength and stress–strain parameters derived from laboratory
triaxial tests on undisturbed samples of completely decomposed Norwood Tuff collected from the landslide site are employed
with finite-element modeling to examine the effects of ground surface deformation patterns on the yielding behavior of the
slide mass. The numerical results indicate a gradual retreat of the yield zone with progressive landslide deformation, which
eventually becomes concentrated within the accumulation zone of the landslide, compared to a well-developed yield zone within
the entire slide mass at the onset of landslide movement. Limit equilibrium stability analyses along potential sliding surfaces
of extent limited within the yield zone of the displaced slide mass produce lower safety factors than an analysis based on
the original sliding surface comprising the entire slide mass. 相似文献
9.
Monitored and simulated variations in matric suction during rainfall in a residual soil slope 总被引：1，自引：0，他引：1
Aurelian C. Trandafir Roy C. Sidle Takashi Gomi Toshitaka Kamai 《Environmental Geology》2008,55(5):951-961
This research combines field, laboratory and numerical investigations to estimate the development of a wetting front within
a 1.2 m residual soil mantle on a steep forested slope during rainfall events. The field-monitored variations in matric suction
due to rain-water infiltration during various events revealed that the maximum infiltration rate was much higher when the
wetting front resided in the upper 20 cm of soil compared to the case when the wetting front advanced to depths > 20 cm. Laboratory
investigations on soil hydraulic properties (i.e., soil water characteristic curve, and hydraulic conductivity) were useful
to establish the parameters of a multilayer finite-element model for one-dimensional vertical infiltration. These parameters
were subsequently calibrated by matching the predicted and field measured transient pore water pressure responses during actual
rainstorms with irregular rainfall patterns. The calibrated simulation model was used to assess the migration of the wetting
front under uniform rainfall with different intensities. Based on the numerical results, a hyperbolic equation was developed
to predict the duration of uniform rainfall required for the propagation of wetting front to a certain depth for a given rainfall
intensity. The proposed equation was subsequently tested against field-monitored advancements of the wetting front during
real rainstorms with variable rainfall intensity. 相似文献
10.
This paper examines in terms of seismic performance, the effectiveness of anchor reinforcement against gravity retaining walls used to stabilize a dry homogenous fill slope in earthquake-prone environment. Both analyzed stabilizing measures have the same design yield acceleration estimated from a limit equilibrium approach. The earthquake-induced displacements are calculated using a sliding block formulation of the equation of motion. Sliding failure along the base of the gravity retaining wall and rotational failure of the soil active wedge behind the wall, as well as rotational failure of the slide mass of the anchor-reinforced slope were considered in the present formulation. For the specific characteristics of the analyzed fill slope and input horizontal ground motion, the slope reinforced with anchors appears to experience vertical and horizontal seismic displacements at slope crest smaller by 12% and respectively, 32% than the vertical and horizontal earthquake-induced deformations estimated at the top of the active wedge behind the gravity retaining wall. 相似文献