71 research outputs found
Entity Extraction from Unstructured Data on the Web
No full textA large number of web pages contain information about entities in lists where the lists are represented in textual form. Textual lists contain implicit records of entities. However, the field values of such records cannot easily be separated or extracted by automatic processes. This, therefore, remains a challenging research problem in the literature. Previous studies in the literature relied mainly on probabilistic graph-based models to capture the attributes and the likely structures of implicit records in a list. However, one of the important limitations of existing methods is that the structures of the records in input lists were implicitly encoded via training data which was manually created. This thesis aims to investigate novel techniques to acquire automatically information about entities from implicit records embedded in textual lists on the web. This thesis introduces a self-supervised learning framework which exploits both existing data in a knowledge base and the structural similarity between sequences in lists to build an extraction model automatically. In the proposed framework, initial labels for candidate field values are created and assigned to generate label sequences. Then, the structure of implici
Has natural radioactivity contributed to the evolution of living organisms? Validation of a dedicated calculation scheme (for isotopic concentrations and deposited energies) on Oklo's natural nuclear reactors
No full textInternational audienceIn October 2018, the French Society of Nuclear Energy (SFEN/PACA) organized a conference-debate entitled “What happened two billion years ago where present-day Gabon is located? Has Nuclear Power contributed to the development of Life on Earth?” Our contribution to this reflection concerns the possible impact of radiation emitted from radioactive media on the early evolution of living organisms and may also be useful for research on the storage of radioactive waste. This article concerns the qualification of a calculation scheme for isotopic concentrations and energy deposits in Oklo's natural nuclear reactors or any other naturally radioactive environment. Our work has been carried out using a calculation scheme involving the Monte Carlo software TRIPOLI-4® [TRIPOLI-4 R, CEA, EDF and AREVA reference Monte Carlo code, https://doi.org/10.1016/j.anucene.2014. 07.053; TRIPOLI-4 R, Version 4 Manuel de l’utilisateur. Rapport CEA-R-6170 (2008); in French] for the propagation of neutrons and gamma rays in matter and the MENDEL software [DARWIN: An Evolution Code System for a Large Range of Applications, CEA, https://doi.org/10.1080/00223131.2000.10875009; MENDEL depletion code, https://doi.org/10.1051/snamc/201402409] which deals with the evolution over time of the concentrations of nuclides formed in a material subjected to neutron irradiation. The precision achieved by our methodology will allow to carry out calculations of deposited energy to contribute to the debate on this possible effect of nuclear power on the evolution of Life
Use of correlations for neutron induced fission yields in DARWIN/PEPIN2 Uncertainty Quantification
No full textUncertainty quantification on Decay Heat is of utmost importance for the safety evaluations linked to nuclear waste management. International nuclear data libraries like JEFF, ENDF/B or JENDL provide evaluations on independent fission yields, but generally no correlations between those fission yields. With those data, independent fission yields can be considered as the most important contributor to the Decay Heat uncertainty. Nevertheless, other data are available, like correlation matrices for some fissile systems, or the use of fission yields by mass. Complete correlation matrices appear in nuclear data libraries, like JEFF-4, but are still very scares as only the most prominent fissile systems for nuclear reactor applications have been added. Another approach is to consider the use of the fission yields by mass, which uncertainty is smaller than those of independent fission yields, and adding a constraint when propagating uncertainties. In the work, we show the impact of considering the fission yields by mass, as it was implemented in DARWIN/PEPIN2.4.8. We compare DARWIN/PEPIN2.4.8 results, obtained on a first order direct perturbation approach, with a random sampling method through the use of an URANIE/MENDEL scheme
Uncertainty quantification of alpha and gamma emission spectra
No full textInternational audienceLe travail consiste en une comparaison MENDEL/DARWIN sur la propagation d'incertitudes depuis les données nucléaires de base jusqu'aux raies d'émission des spectres alpha et gamma.Les deux méthodes (déterministes et stochastiques) seront décrites et comparées sur des cas simples (fission élémentaire et un cas de combustible irradié)
Determining the risks of the process construction in border areas
No full textIn all phases of the project, there are always events and conditions occurring that directly or indirectly affect the implementation of the project, causing the project to fail to achieve the target of the proposed project subject. Such events and conditions are called project risks. The more human society develops, the more diverse, rich, and complex human activities become. Therefore, risks are increasingly complex and have negative impacts on people’s lives. Construction work is a special product. Therefore there are more and more risks that are hidden in the construction process. Especially when projects are placed in remote, mountainous, or border areas, the risks become more complex and diverse. Hence, if risks are identified quickly and accurately, managers can reduce the level of risk in the process. Then, people can also suggest some solutions to reduce the risks. The goal of this paper is to propose and evaluate the risk factors of the construction process in the border district, Quang Nam Province, by applying the Exploratory Factor Analysis (EFA) method. This study tried to collect data analyze qualitative and quantitative risk factors. The results showed that the collected survey data is meaningful
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