Enhanced climate instability in the North Atlantic and southern Europe during the Last Interglacial

Considerable ambiguity remains over the extent and nature of millennial/centennial-scale climate instability during the Last Interglacial (LIG). Here we analyse marine and terrestrial proxies from a deep-sea sediment sequence on the Portuguese Margin and combine results with an intensively dated Italian speleothem record and climate-model experiments. The strongest expression of climate variability occurred during the transitions into and out of the LIG. Our records also document a series of multi-centennial intra-interglacial arid events in southern Europe, coherent with cold water-mass expansions in the North Atlantic. The spatial and temporal fingerprints of these changes indicate a reorganization of ocean surface circulation, consistent with low-intensity disruptions of the Atlantic meridional overturning circulation (AMOC). The amplitude of this LIG variability is greater than that observed in Holocene records. Episodic Greenland ice melt and runoff as a result of excess warmth may have contributed to AMOC weakening and increased climate instability throughout the LIG

Ensemble and fuzzy techniques applied to imbalanced traffic congestion datasets a comparative study

Class imbalance is among the most persistent complications which may confront the traditional supervised learning task in real-world applications. Among the different kind of classification problems that have been studied in the literature, the imbalanced ones, particularly those that represents real-world problems, have attracted the interest of many researchers in recent years. In order to face this problems, different approaches have been used or proposed in the literature, between then, soft computing and ensemble techniques. In this work, ensembles and fuzzy techniques have been applied to real-world traffic datasets in order to study their performance in imbalanced real-world scenarios. KEEL platform is used to carried out this study. The results show that different ensemble techniques obtain the best results in the proposed datasets. Document type: Part of book or chapter of boo

Ocena hydrochemiczna i zanieczyszczenie wód gruntowych w strefie klimatu suchego – przykład poziomu wodonośnego z turonu (późna kreda) w regionie Béchar w południowo-zachodniej Algierii

Groundwater samples from Turonian aquifer of Béchar region were evaluated as drinking and irrigation water sources. physicochemical parameters including pH, EC, TH, Na+, Ca2+, Mg2+, Cl–, SO4 2– and NO3 – were determined for 16 water sampling points. These characterizations show that the groundwater is fresh to brackish, slightly alkaline and the major ions are Na+, Ca2+, Mg2+, Cl– and SO4 2–. According to WHO standards, 50% of the analysed water are suitable as a drinking source while the other samples are not in compliance with drinking water standards. This non-compliance is basically due to the high concentrations of Na+, Cl–, and SO4 2– requesting further treatment to reach the stringent standards. According to the results of nitrate concentrations, anthropogenic source seems to influence the groundwater quality. The present study shows that Béchar groundwater may represent an important drinking and irrigation water source. However, a specific management strategy should be adapted in order to avoid the contamination by anthropogenic sources.Oceniano przydatność wód gruntowych z wieku/piętra turonu w regionie Béchar do nawadniania i zaopatrzenia ludności w wodę pitną. W próbkach wody z 16 stanowisk oznaczano pH, przewodność elektrolityczną (EC), całkowitą twardość (TH), Na+, Ca2+, Mg2+, Cl–, SO4 2– i NO3 –. Analiza wykazała, że wody gruntowe są słodkie do słonawych, alkaliczne, a głównymi jonami są: Na+, Ca2+, Mg2+, Cl– i SO4 2–. Według norm WHO 50% analizowanych próbek spełnia wymogi stawiane wodzie przeznaczonej do picia. W pozostałych próbkach zbyt duże stężenie Na+, Cl– i SO4 2– wskazuje na konieczność uzdatniania wody, aby osiągnęła ona wymagane standardy. Stężenie azotanów wskazuje na antropogeniczne źródło zanieczyszczenia tymi jonami. Badania dowodzą, że wody gruntowe Béchar mogą być źródłem wody do nawadniania i do celów spożywczych. Należy jednak przyjąć szczególną strategię gospodarowania wodą, aby uniknąć zanieczyszczenia ze źródeł antropogenicznych

Application of coupled code technique to a safety analysis of a standard MTR research reactor

Accident analyses in nuclear research reactors have been performed, up to now, using simple computational tools based on conservative physical models. These codes, developed to focus on specific phenomena in the reactor, were widely used for licensing purposes. Nowadays, the advances in computer technology make it possible to switch to a new generation of computational tools that provides more realistic description of the phenomena occurring in a nuclear research reactor. Recent International Atomic Energy Agency (IAEA) activities have emphasized the maturity in using Best Estimate (BE) Codes in the analysis of accidents in research reactors. Indeed, some assessments have already been performed using BE thermal–hydraulic system codes such as RELAP5/Mod3. The challenge today is oriented to the application of coupled code techniques for research reactors safety analyses. Within the framework of the current study, a Three-Dimensional Neutron Kinetics Thermal–Hydraulic Model (3D-NKTH) based on coupled PARCS and RELAP5/Mod3.3 codes has been developed for the IAEA High Enriched Uranium (HEU) benchmark core. The results of the steady state calculations are sketched by comparison to tabulated results issued from the IAEA TECDOC 643. These data were obtained using conventional diffusion codes as well as Monte Carlo codes. On the other hand, the transient analysis was assessed with conventional coupled point kinetics–thermal–hydraulic channel codes such as RELAP5 stand alone, RETRAC-PC, and PARET codes. Through this study, the applicability of the coupled code technique is emphasized with an outline of some remaining challenges