720 research outputs found

    Po-production in lead: A benchmark between Geant4, FLUKA and MCNPX

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    On the last SATIF a comparison between the measured activities of the polonium isotopes Po-208, Po-209 and Po-210 and the simulated results using MCNPX2.7.0 was presented. The lead samples were cut from the SINQ spallation target at the Paul Scherrer Institut (PSI) and irradiated in 2000/2001 by 575 MeV protons. The Po-isotopes were separated using radiochemical methods by the group of D. Schumann at PSI and measured. Choosing the default model in MCNPX, Bertini-Dresner, the prediction underestimated the measured activities by up to several orders of magnitude. Therefore the Li\`ege intranuclear-cascade model (INCL4.6) coupled to the de-excitation model ABLA07 were implemented into MCNPX2.7.0 and very good agreement was found to the measurement. The reason for the disagreement was traced back to a suppression of alpha reactions on the lead isotopes leading to Po and neglecting the triton capture on Pb-208, which leads to Pb-210 and decays into Po-210 with a much longer life time (22.3 years) than the decay of Po-210 itself (138 days). The prediction of the Po-isotope activities turns out to be a sensitive test for models and codes as it requires the accurate treatment of reaction channels not only with neutrons, protons and pions but also with alphas and tritons, which are not considered in intra-nuclear cascade models of the first generation. Therefore it was decided to perform a benchmark by comparing the results obtained with MCNPX2.7.0 using INCL4.6/ABLA07 to the predictions of FLUKA and Geant4. Since the model of the SINQ spallation source requires an elaborate geometry a toy model was setup. The toy model has a simplified geometry preserving the main features of the original geometry. The results for the activities of the three Po-isotopes and Pb-210 as well as the energy spectra for alphas and tritons obtained with the three particle transport Monte Carlo codes are presented.Comment: 15 pages, 11 figures, Presented paper at the 13th Meeting of the task-force on Shielding aspects of Accelerators, Targets and Irradiation Facilities (SATIF-13), HZDR, October 10-12, 2016, Dresden, German

    Analysis of the Kenyan economy: an input-output approach

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    Since the beginning of the 2008 economic crisis, economic growth and development have been in the forefront of economic research. In a global context, the highest levels of poverty as well as malnutrition problems are found in sub-Saharan African countries. Social Accounting Matrices (SAMs) are useful tools to describe the economic situation of these countries, the interactions among economic agents and to support policymakers in implementing their policies. The paper shows the macro- and micro-economic indicators of Kenya, which can be directly extracted from the described SAM 2017 for Kenya The analysis of the SAM multipliers shows that agri-food multipliers are in general above the average reflecting the strength of backward and forward linkages of Kenya’s economy

    Preliminary Report on the Study of Beam-Induced Background Effects at a Muon Collider

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    Physics at a multi-TeV muon collider needs a change of perspective for the detector design due to the large amount of background induced by muon beam decays. Preliminary studies, based on simulated data, on the composition and the characteristics of the particles originated from the muon decays and reaching the detectors are presented here. The reconstruction performance of the physics processes HbbˉH\to b\bar b and ZbbˉZ\to b\bar b has been investigated for the time being without the effect of the machine induced background. A preliminary study of the environment hazard due to the radiation induced by neutrino interactions with the matter is presented using the FLUKA simulation program

    Matrice de comptabilité sociale désagrégée de l'économie sénégalaise en 2014

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    Ce rapport documente une Matrice de comptabilité sociale (MCS) désagrégée de l'économie sénégalaise en 2014. Elle comprend 218 comptes répartis en 55 activités économiques (dont 14 comptes de ménages en tant que producteurs), 57 comptes de produits commercialisés et 9 comptes de produits autoconsommés, 3 catégories de travail distingué selon la qualification (qualifié, semi-qualifié et non-qualifié) dans 14 régions sénégalaises et 1 région représentant le reste du monde; 5 comptes de capital (agricoles, non agricoles, terre non irriguée, terre irriguée et élevage), 5 comptes d'impôts et taxes (directs, indirects, ventes, facteur travail et importations), 33 catégories de ménages représentatifs (régionalisés) et un compte de marges, un compte d'épargne-investissement, 4 comptes allouant les investissements (routes, irrigation, autres infrastructures, reste des investissements), un compte d'entreprises, du gouvernement et du reste du monde.JRC.D.4-Economics of Agricultur

    Estimation of food demand parameters in Kenya

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    A Quadratic Almost Ideal Demand System (QUAIDS) approachJRC.D.4-Economics of Agricultur

    Biomarcadores etológicos no invasivos de estrés ambiental: estudio comparativo en dos teleosteos de ecosistemas de la región pampeana argentina

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    Mediante un dispositivo de registro automático se estudió el efecto de la exposición a soluciones subletales de Cd2+ (0.3 mg. L'1) sobre algunos parámetros etológicos de juveniles de Cyprinus carpió (carpa común) y de Astyanax fasciatus (“mojarra”). Se evaluó el efecto del metal sobre la actividad natatoria total y las preferencias altitudinales y laterales de los peces. Los tres parámetros se registraron simultáneamente mediante un dispositivo original. Se evaluaron los niveles “normales” o estándar de dichos parámetros (los peces en agua potable, control) y los alcanzados por los mismos individuos tras su exposición al tóxico de referencia (Cd). El metal provocó una depresión de la actividad natatoria total alcanzando una magnitud comparable en ambas especies. La preferencia altitudinal, también resultó modificada: C. carpió se halló con mayor frecuencia en la capa superior de los acuarios mientras que A. fasciatus se ubicó en las inferiores. En cuanto a la preferencia lateral, los individuos de ambas especies evitaron la franja vertical donde se producía el goteo de la solución de Cd; si bien esta respuesta espacial de los animales no siguió un patrón definido fue más marcada en las carpas. Todas las respuestas se pusieron de manifiesto inmediatamente después de haberse iniciado la exposición al Cd. El método resultó sensible y apto para el seguimiento de los parámetros etológicos seleccionados. Se concluye que la actividad natatoria y la ubicación espacial de las especies estudiadas, entre otros indicadores, pueden ser considerados como biomarcadores de toxicidad acuática.By means of an automatic recording device, the eífects of the exposure to sublethal Solutions of Cd2+ (0.3 mg. L2) on some ethological parameters of juvenile Cyprinus carpió (common carp) and Astyanaxfasciatus. The effect of the metal was evaluated through three parameters: the total swimming activity and the spatial (lateral and altitudinal) preferences, relative to Controls (fish kept in tap water); they were registered simultaneously by means oían original device. There were determined successively the “normal” or standard levels of those parameters in control fish and those reached by the same individuáis aftertheir exposure to thereferencetoxic (Cd). In both species the metal caused a depression of the total swimming activity in a comparable magnitude. The altitudinal preference was also modified: C. carpió was found more frequently in the superior layer of the aquaria while A. fasciatus was found in the inferior ones. For the lateral preference, the individuáis of both species showed an avoidance behavior of the site of the aquaria where the Cd Solutions was dripping. This response of the animáis didn't follow a defined pattem, but was more marked in the carps. All the evaluated responses to the toxic were detected immediately after the beginning of the exposure to Cd. The method proved to be sensitive and apt for the monitoring of the measured behavioural parameters which makes it a promising tool for biomonitoring purposes. We concluded that the swimming activity and the spatial location preferences of the studied species, among other, may be considered as biomarkers of aquatic toxicity

    The role of bioeconomy sectors and natural resources in EU economies: A social accounting matrix-based analysis approach

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    The bio-based economy will be crucial in achieving a sustainable development, covering all ranges of natural resources. In this sense, it is very relevant to analyze the economic links between the bioeconomic sectors and the rest of the economy, determining their total and decomposed impact on economic growth. One of the major problems in carrying out this analysis is the lack of information and complete databases that allow analysis of the bioeconomy and its effects on other economic activities. To overcome this issue, disaggregated social accounting matrices have been obtained for the highly bio-based sectors of the 28 European Union member states. Using this complex database, a linear multiplier analysis shows the future key role of bio-based sectors in boosting economic development in the EU. Results show that the bioeconomy has not yet unleashed its full potential in terms of output and job creation. Thus, output and employment multipliers show that many sectors related to the bioeconomy are still underperforming compared to the EU average, particularly those with higher value added; although, they are still crucial sectors for the wealth creation

    Policy impact assessment in developing countries using Social Accounting Matrices: the Kenya SAM 2014

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    This paper describes the structure and estimation of a Social Accounting Matrix (SAM) of Kenya for the year 2014. Among its specificities, this SAM includes a very high disaggregation of the agri-food sector and accounts for the double role of households as producers and consumers. Accounting for these characteristics is crucial to provide robust socioeconomic analysis in the context of developing countries. Indeed, this type of database is valuable to perform ex-ante evaluations of economic policies with various economic models and techniques. In this paper, we present an application with a linear multiplier analysis (backward linkages and value chain decomposition). The results show the capacity of the primary sector in Kenya to generate value added and employment, with this growth distributed more intensely in rural households whose main livelihood is semi-subsistence agriculture

    Research of Image Retrieval Technology Based on Annular Moments and Fuzzy Clustering

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    自20世纪70年代以来,在数据库系统和计算机视觉两大研究领域的共同推动下,图像检索技术已逐渐成为一个研究热点。本文在系统学习和掌握基于内容的图像检索领域相关知识的基础上,主要针对图像特征的提取表达,高维图像特征的模糊聚类,相关反馈等技术进行了深入研究,分别提出了相应算法。论文的主要工作包括基于颜色特征和纹理特征的图像检索方法研究,并在已有理论的基础上,针对具体的图像数据库,设计了一个基于环形矩和模糊聚类的图像检索实验系统,并使用Corel图像库对以上检索方法的有效性进行分析和比较。本文主要创新点如下: (1)为了提高检索性能,本文提出一种综合颜色和纹理特征的图像检索方法。在颜色特征方面,提出...Image is an important information carrier, and also an important part of multimedia information. With rapid development of Internet and technologies of computer and multimedia, the number of image data grows in geometric progression. Therefore, how to effectively manage and retrieve large-scale images became a critical problem.Image retrieval has been an active research area since the 1970s, with ...学位:工学硕士院系专业:软件学院_计算机软件与理论学号:2432007115182

    Boosting the Fertilizer Production in Kenya: a CGE analysis

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    Food security remains a key challenge in many Sub-Saharan African countries and in Kenya in particular. Kenya addresses this concern with a noteworthy policy mix, aiming at giving to the agricultural sector a leading task in improving food security. In this paper, through a Computable General Equilibrium (CGE) model specifically modified for the context of developing country analyses, we address the impacts of the construction of a new fertilizer plant on the agricultural sector and the rest of the economy. For the purpose of the study, a desegregated version of a 2014 Social Accounting Matrix (SAM) has been developed. Results suggests that increasing domestic production of fertilizers do not fully achieve the objectives of reducing rural poverty and increasing agricultural production without complementary policies that help small-holder farmers to overcome the backward technology trap and give them better access to input and output markets.JRC.D.4-Economics of Agricultur
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