Search results for "Processes"
showing 10 items of 3831 documents
Lattice-particle simulation of stress patterns in a Rwenzori-type rift transfer zone
2011
Abstract A new 3D spring lattice computer model has been developed and used to calculate the stress-field in the vicinity of a rift transfer zone. The numerical setup is based on the Rwenzori block, a transfer zone in the Western Branch of the East African Rift Valley. The study has two closely related, yet independent aims: primarily to gain insight into the pattern and the causes of the stress field in the Rwenzori area. The second aim is the evaluation of the model itself, based on a comparison of the model results with local geological structures. The simulations calculate the stress in the brittle part of the crust, at the topographic surface and at a depth of 10 km. The model does the…
Seismic moment tensors and regional stress in the area of the December 2013–January 2014, Matese earthquake sequence (Italy)
2014
Abstract The main goal of this study is to provide moment tensor solutions for small and moderate earthquakes of the Matese seismic sequence in southern Italy for the period of December 2013–January 2014. We estimate the focal mechanisms of 31 earthquakes with local magnitudes related to the Matese earthquake seismic sequence (December 2013–January 2014) in Southern-Central Italy which are recorded by the broadband stations of the Italian National Seismic Network and the Mediterranean Very Broadband Seismographic Network (MedNet) run by the Istituto Nazionale di Geofisica e Vulcanologia (INGV). The solutions show that normal faulting is the prevailing style of seismic deformation in agreeme…
Reproducibility of trace element time-series (Na/Ca, Mg/Ca, Mn/Ca, Sr/Ca, and Ba/Ca) within and between specimens of the bivalve Arctica islandica – …
2017
Abstract Trace element time-series in bivalve mollusk shells and other (biogenic) materials can potentially serve as environmental proxies. Yet, the applicability of element-to-calcium ratios is often challenging, because non-environmental factors such as vital effects distort or mask environmental signals. If a trace element time-series is driven by an environmental factor, it should be reproducible within and between coeval specimens of the same species. In the present study, we tested whether time-series of trace element-to-calcium ratios can be reproduced within and between coeval specimens of the bivalve Arctica islandica and thus whether an external signal is encoded in the temporal v…
Controls on strontium and barium incorporation into freshwater bivalve shells ( Corbicula fluminea )
2017
Abstract Trace elements of bivalve shells can potentially serve as proxies of environmental change. However, to reconstruct past environments using the geochemical properties of the shells and determine the degree to which the element levels are biologically influenced, it is essential to experimentally determine the relationship between environmental variables and the element composition of the shells. To disentangle possible controls on the incorporation of strontium and barium into freshwater bivalve shells, we conducted controlled laboratory experiments using the extremely salinity and temperature tolerant Asian clam, Corbicula fluminea as a model species. Bivalves were reared for five …
Recent advances in space-time statistics with applications to environmental data: An overview
2003
[1] This paper introduces a special section based on general environmental scientific problems, with a particular focus on using atmospheric data. All the papers and authors provide the methodology to study, analyze, predict, and evaluate the spatial-temporal behavior and the complicated spatial-temporal structure of the data. The overall aim is to present up-to-date developments in spatial and spatiotemporal statistics in the field of the atmosphere, to present on-going research, and to discuss important problems to be addressed in the near future.
Filament sets and homogeneous continua
2007
Abstract New tools are introduced for the study of homogeneous continua. The subcontinua of a given continuum are classified into three types: filament , non-filament , and ample , with ample being a subcategory of non-filament. The richness of the collection of ample subcontinua of a homogeneous continuum reflects where the space lies in the gradation from being locally connected at one extreme to indecomposable at another. Applications are given to the general theory of homogeneous continua and their hyperspaces.
Oceanographic control on shell growth of Arctica islandica (Bivalvia) in surface waters of Northeast Iceland — Implications for paleoclimate reconstr…
2015
Absolutely dated, annually resolved sea surface temperature records from middle to higher latitudes covering long time intervals are crucial to better understand the climate system. Such data can potentially be obtained from variations in shell growth of long-lived bivalves such as Arctica islandica. This study presents the first statistically robust 178-yr long composite chronology (covering 1835–2012) based on sixteen live-collected and subfossil specimens of A. islandica from unpolluted, shallow waters of Northeast Iceland. Between 1875 and 1996, up to 43% of the variation in annual shell growth was explained by SST during February to September. Faster growth occurred when temperatures w…
Numerical-Experimental Study Regarding the Single Point Incremental Forming Process
2021
The present paper proposes a numerical-experimental comparative study on the single point incremental forming process. A DC04 steel sheet with a thickness of 0.6 mm was used for both the numerical simulation using the finite element method and the experimental research. The type of trajectory used was a spiral trajectory and the finished part obtained was a truncated cone-shaped part. The analysis program used for simulation was Ls-Dyna. The simulations were performed in several variants: with a fixed mesh and with an adaptive mesh, using two different element formulations: 25 (Belytschko-Tsay formulation with thickness stretch) and -16 (fully integrated shell element modified for higher ac…
Hydrodynamics with spin in bacterial suspensions
2016
We describe a new kind of self-propelling motion of bacteria based on the cooperative action of rotating flagella on the surface of bacteria. Describing the ensemble of rotating flagella in the framework of the hydrodynamics with spin the reciprocal theorem of Stokesian hydrodynamics is generalized accordingly. The velocity of the self-propulsion is expressed in terms of the characteristics of the vector field of flagella orientation and it is shown that unusually high velocities of \textit{Thiovulum majus} bacteria may be explained by the cooperative action of the rotating flagella. The expressions obtained enable us to estimate the torque created by the rotary motors of the bacterium and …
Surface emissivity retrieval from Digital Airborne Imaging Spectrometer data
2002
[1] A study has been carried out on the most recent algorithms for the estimation of land surface emissivity (e) using high-resolution data (Digital Airborne Imaging Spectrometer, DAIS) over the Rhine Valley (France) and Castilla La Mancha (Spain). Three published methods have been applied for extracting absolute spectral emissivity information from images recorded during the DAISEX experiment in 1999. They are NDVI Thresholds Method (NDVITHM), Normalized Emissivity Method (NEM) and Temperature/Emissivity Separation (TES). These lather two methods were originally designed to work over geological surfaces. Five methods have been used for extracting relative spectral emissivity. They are temp…