http://hdl.handle.net/2117/3953 Wed, 22 May 2013 20:35:25 GMT 2013-05-22T20:35:25Z webmaster.bupc@upc.edu Universitat Politècnica de Catalunya. Servei de Biblioteques i Documentació no http://hdl.handle.net/2117/7932 Title: Meso-mechanical analysis of the fracture of concrete specimens in mixed mode Authors: Rodríguez, Mariana; López Garello, Carlos María; Carol, Ignacio; Caner, Ferhun Cem Abstract: This paper describes recent numerical simulation results of some experiments carried out by Nooru-Mohamed to study mixed mode fracture of concrete. The numerical simulation is based on a meso-mechanical model developed in the group of Mechanics of Materials UPC, which represents the largest aggregate particles explicitly, and represent cracks in a discrete manner by inserting zero-tickness interface elements in all potential crack trajectories a priori of the analysis. Wed, 30 Jun 2010 17:35:35 GMT http://hdl.handle.net/2117/7932 2010-06-30T17:35:35Z Rodríguez, Mariana; López Garello, Carlos María; Carol, Ignacio; Caner, Ferhun Cem no Mixed mode of fracture in concrete, Meso-mechanics, finite element method, interface elements This paper describes recent numerical simulation results of some experiments carried out by Nooru-Mohamed to study mixed mode fracture of concrete. The numerical simulation is based on a meso-mechanical model developed in the group of Mechanics of Materials UPC, which represents the largest aggregate particles explicitly, and represent cracks in a discrete manner by inserting zero-tickness interface elements in all potential crack trajectories a priori of the analysis. http://hdl.handle.net/2117/7669 Title: Comparison between PENELOPE and electron Monte Carlo simulations of electron fields used in the treatment of conjunctival lymphoma Authors: Brualla Barbera, Lorenzo; Palanco Zamora, R.; Witting, A.; Sempau Roma, Josep; Sauerwein, W. Abstract: For the treatment of conjunctival lymphoma in the early stages, external beam radiotherapy offers a curative approach. Such treatment requires the use of highly conformed small radiation beams. The beam size is so small that even advanced treatment planning systems have difficulties in calculating dose distributions. One possible approach for optimizing the treatment technique and later performing treatment planning is by means of full Monte Carlo (MC) simulations. In this paper, we compare experimental absorbed dose profiles obtained with a collimator used at the University Hospital Essen, with MC simulations done with the general-purpose radiation transport code PENELOPE. The collimator is also simulated with the hybrid MC code electron Monte Carlo (eMC) implemented in the commercial treatment planning system Eclipse (Varian). The results obtained with PENELOPE have a maximum difference with experimental data of 2.3%, whereas the eMC code differs systematically from the experimental data about 7% in the penumbra tails. We also show that PENELOPE simulations are able to obtain absorbed dose maps with an equivalent statistical uncertainty to the one found with eMC in similar CPU times. Tue, 15 Jun 2010 10:30:46 GMT http://hdl.handle.net/2117/7669 2010-06-15T10:30:46Z Brualla Barbera, Lorenzo; Palanco Zamora, R.; Witting, A.; Sempau Roma, Josep; Sauerwein, W. no For the treatment of conjunctival lymphoma in the early stages, external beam radiotherapy offers a curative approach. Such treatment requires the use of highly conformed small radiation beams. The beam size is so small that even advanced treatment planning systems have difficulties in calculating dose distributions. One possible approach for optimizing the treatment technique and later performing treatment planning is by means of full Monte Carlo (MC) simulations. In this paper, we compare experimental absorbed dose profiles obtained with a collimator used at the University Hospital Essen, with MC simulations done with the general-purpose radiation transport code PENELOPE. The collimator is also simulated with the hybrid MC code electron Monte Carlo (eMC) implemented in the commercial treatment planning system Eclipse (Varian). The results obtained with PENELOPE have a maximum difference with experimental data of 2.3%, whereas the eMC code differs systematically from the experimental data about 7% in the penumbra tails. We also show that PENELOPE simulations are able to obtain absorbed dose maps with an equivalent statistical uncertainty to the one found with eMC in similar CPU times. http://hdl.handle.net/2117/7648 Title: PenMesh-Monte Carlo radiation transport simulation in a triangle mesh geometry Authors: Badal Soler, Andreu; Kyprianou, Iacovos; Banh, Diem Phuc; Badano, Aldo; Sempau Roma, Josep Abstract: We have developed a general-purpose Monte Carlo simulation code, called penMesh, that combines the accuracy of the radiation transport physics subroutines from PENELOPE and the flexibility of a geometry based on triangle meshes. While the geometric models implemented in most general-purpose codes-such as PENELOPE's quadric geometry-impose some limitations in the shape of the objects that can be simulated, triangle meshes can be used to describe any free-form (arbitrary) object. Triangle meshes are extensively used in computer-aided design and computer graphics. We took advantage of the sophisticated tools already developed in these fields, such as an octree structure and an efficient ray-triangle intersection algorithm, to significantly accelerate the triangle mesh ray-tracing. A detailed description of the new simulation code and its ray-tracing algorithm is provided in this paper. Furthermore, we show how it can be readily used in medical imaging applications thanks to the detailed anatomical phantoms already available. In particular, we present a whole body radiography simulation using a triangulated version of the anthropomorphic NCAT phantom. An example simulation of scatter fraction measurements using a standardized abdomen and lumbar spine phantom, and a benchmark of the triangle mesh and quadric geometries in the ray-tracing of a mathematical breast model, are also presented to show some of the capabilities of penMesh. Mon, 14 Jun 2010 12:22:43 GMT http://hdl.handle.net/2117/7648 2010-06-14T12:22:43Z Badal Soler, Andreu; Kyprianou, Iacovos; Banh, Diem Phuc; Badano, Aldo; Sempau Roma, Josep no We have developed a general-purpose Monte Carlo simulation code, called penMesh, that combines the accuracy of the radiation transport physics subroutines from PENELOPE and the flexibility of a geometry based on triangle meshes. While the geometric models implemented in most general-purpose codes-such as PENELOPE's quadric geometry-impose some limitations in the shape of the objects that can be simulated, triangle meshes can be used to describe any free-form (arbitrary) object. Triangle meshes are extensively used in computer-aided design and computer graphics. We took advantage of the sophisticated tools already developed in these fields, such as an octree structure and an efficient ray-triangle intersection algorithm, to significantly accelerate the triangle mesh ray-tracing. A detailed description of the new simulation code and its ray-tracing algorithm is provided in this paper. Furthermore, we show how it can be readily used in medical imaging applications thanks to the detailed anatomical phantoms already available. In particular, we present a whole body radiography simulation using a triangulated version of the anthropomorphic NCAT phantom. An example simulation of scatter fraction measurements using a standardized abdomen and lumbar spine phantom, and a benchmark of the triangle mesh and quadric geometries in the ray-tracing of a mathematical breast model, are also presented to show some of the capabilities of penMesh. http://hdl.handle.net/2117/7390 Title: Natural and anthropogenic radionuclides in airborne particulate samples collected in Barcelona (Spain) Authors: Valles Murciano, M. Isabel; Camacho García, Antonia; Ortega Aramburu, Miguel Javier; Serrano, Ivana; Blázquez Pérez, Sonia M.; Perez, S Thu, 27 May 2010 11:02:52 GMT http://hdl.handle.net/2117/7390 2010-05-27T11:02:52Z Valles Murciano, M. Isabel; Camacho García, Antonia; Ortega Aramburu, Miguel Javier; Serrano, Ivana; Blázquez Pérez, Sonia M.; Perez, S no http://hdl.handle.net/2117/7314 Title: Analysis of outdoor radon pregeny concentration measured at the Spanish radioactive aerosol automatic monitoring network Authors: Arnold Arias, Dèlia; Vargas Drechsler, Arturo; Ortega Aramburu, Miguel Javier Abstract: An analysis of 10-year radon progeny data,provided by the Spanish automatic radiological surveillance network, in relation to meteorology is presented. Results show great spatial variability depending mainly on the station location and thus,the surrounding radon exhalation rate. Hourly averages show the typical diurnal cycle with an early morning maximum and a minimum at noon,except for one mountain station, which shows an inverse behaviour. Monthly averaged values show lower concentrations during months with higher atmospheric instability. Wed, 19 May 2010 09:28:30 GMT http://hdl.handle.net/2117/7314 2010-05-19T09:28:30Z Arnold Arias, Dèlia; Vargas Drechsler, Arturo; Ortega Aramburu, Miguel Javier no An analysis of 10-year radon progeny data,provided by the Spanish automatic radiological surveillance network, in relation to meteorology is presented. Results show great spatial variability depending mainly on the station location and thus,the surrounding radon exhalation rate. Hourly averages show the typical diurnal cycle with an early morning maximum and a minimum at noon,except for one mountain station, which shows an inverse behaviour. Monthly averaged values show lower concentrations during months with higher atmospheric instability. http://hdl.handle.net/2117/7313 Title: Analysis of radon origin by backward atmospheric transport modelling Authors: Arnold Arias, Dèlia; Vargas Drechsler, Arturo; Vermeulen, A.T.; Verheggen, B.; Seibert, P. Abstract: This work shows how ambient radon concentrations measured at Cabauw station in central Netherlands are influenced by transport from different regions under typical transport conditions occurring during April and November, 2007 by means of atmospheric Lagrangian particle dispersion modelling in a receptor-oriented approach. Four specific regions have been isolated to assess their contribution to the modelled radon ambient concentrations at Cabauw, and two different radon flux assumptions. Westerly flows coming from the ocean are poor in radon and do not increase radon air concentrations unless there is some fetch over the British Isles. Continental transport, mainly from eastern and southern Europe, significantly increases radon background concentrations, reaching increments of 3 Bq m-3. A constant 0.66 atoms cm-2 s-1 radon flux over land and zero over water bodies is a good approximation for the source term in order to study regional contributions and modulation of the radon background. Wed, 19 May 2010 09:00:53 GMT http://hdl.handle.net/2117/7313 2010-05-19T09:00:53Z Arnold Arias, Dèlia; Vargas Drechsler, Arturo; Vermeulen, A.T.; Verheggen, B.; Seibert, P. no This work shows how ambient radon concentrations measured at Cabauw station in central Netherlands are influenced by transport from different regions under typical transport conditions occurring during April and November, 2007 by means of atmospheric Lagrangian particle dispersion modelling in a receptor-oriented approach. Four specific regions have been isolated to assess their contribution to the modelled radon ambient concentrations at Cabauw, and two different radon flux assumptions. Westerly flows coming from the ocean are poor in radon and do not increase radon air concentrations unless there is some fetch over the British Isles. Continental transport, mainly from eastern and southern Europe, significantly increases radon background concentrations, reaching increments of 3 Bq m-3. A constant 0.66 atoms cm-2 s-1 radon flux over land and zero over water bodies is a good approximation for the source term in order to study regional contributions and modulation of the radon background. http://hdl.handle.net/2117/7309 Title: Activity size distributions for long-lived radon decays products in aerosols collected in Barcelona (Spain) Authors: Camacho García, Antonia; Valles Murciano, M. Isabel; Vargas Drechsler, Arturo; González Perosanz, M.; Ortega Aramburu, Miguel Javier Abstract: The activity median aerodynamic diameters(AMADs)oflong-lived radon decay product(210Pb, 210Po) in aerosols collected in the Barcelona area(NortheastSpain)during the period from April 2006 toFebruary 2008 arepresented.The 210Po mean AMAD was 420nm, while the 210Pb mean AMAD was 500nm. The temporal evolution of 210Pb and 210Po AMADs shows maxima in autumn and winter and minima in spring and summer. 210Pb AMAD are being used to estimate the mean-residence time of atmospheric aerosols. Tue, 18 May 2010 13:51:45 GMT http://hdl.handle.net/2117/7309 2010-05-18T13:51:45Z Camacho García, Antonia; Valles Murciano, M. Isabel; Vargas Drechsler, Arturo; González Perosanz, M.; Ortega Aramburu, Miguel Javier no The activity median aerodynamic diameters(AMADs)oflong-lived radon decay product(210Pb, 210Po) in aerosols collected in the Barcelona area(NortheastSpain)during the period from April 2006 toFebruary 2008 arepresented.The 210Po mean AMAD was 420nm, while the 210Pb mean AMAD was 500nm. The temporal evolution of 210Pb and 210Po AMADs shows maxima in autumn and winter and minima in spring and summer. 210Pb AMAD are being used to estimate the mean-residence time of atmospheric aerosols.